Adult-FanFiction.org : Cartoons

Fistbump (a Pinecest story)	By : Edward_or_Ford Category: +G through L > Gravity Falls Views: 13063 -:- Recommendations : 1 -:- Currently Reading : 0
Disclaimer: I do not own Gravity Falls or its characters. I will not earn any money from this story.

Chapter List
- 2
- 3
- 4
The alarm sounded, and Dipper woke up quickly. As usual, Mabel took much longer to rouse, so as usual Dipper left the alarm going and started getting up. Mabel groggily tossed her pillows in the direction of the end table, to no avail.
“Come on, Mabes,” called Dipper. “We need to get going. Up and at ‘em!” while he tossed one of Mabel’s pillows back at her head.
“Hey!” complained Mabel’s muffled voice, her head buried face-down on the mattress. She half-raised her head and didn’t appear to process where she was. Not seeming to care regardless, her face fell back to the bed.
“C’mon, Mabel,” Dipper said, more gently this time. He sat down on Mabel’s bed beside her. Not so much as a twitch came from her. He grinned slowly, as he knew what do to get her up.
Trying to keep a tune as best as his still-cracking adolescent voice allowed, he started in. “Happy Birth-day to uuussss…” he sang quietly, then paused. A smile crept across Mabel’s face.
“Happy Birth-day to uuusssssss…” This time, Mabel managed to match Dipper’s rising volume, pushing herself up with one arm while she struggled to clear the sleep from her eyes and hair out of her face with her other hand.
“Happy BIRTH-day dear MabelandDipperrrrrrrr” (or “DipperandMabelllllllllll”, depending on which of the now-loud voices you were listening to) as Mabel sat up gamely, then pushed herself up to her knees. Dipper rose off the bed and stood, and they moved to the final line.
“HAAAAAPPY BIRTH DAY TO UUUUUUUUSSSSSSSS!!!!!!” they bellowed together, Mabel now standing tall on the bed, and Dipper jumping up to join her. Then they fell down to the bed in a fit of childish laughter. They had thought themselves very clever when they created their own birthday song when they turned four years old. Now ten years later, they still loved the tradition of singing it together. For the last several years, the introverted Dipper had always felt self-conscious letting anyone but Mabel hear him sing, so here in the hotel room was the perfect place to be free.
Mabel was delighted to see Dipper be able let out his silly side, and decided to pounce on him. They hadn’t play-wrestled in a long time, but Mabel still held the advantage of being far less ticklish than Dipper. It had never taken Mabel long to force Dipper into a squirming mass of total defeat, and this turned out to be no exception. After she accepted his surrender, she affectionately punched his arm.
“Thanks, little bro,” Mabel teased, rubbing in how she was born five minutes before Dipper, and thus was his older sister. “I’m up now!”
“So is this whole floor in the hotel, probably,” Dipper added, trying to regain his breath. He was still in a fetal position, looking like he was expecting another tickle attack shortly. “I think we’d better get out of here quick before we get complaints.”
“Ah, stop ackin’ all cray cray!” Mabel replied happily. “It’s our birthday! We’re allowed to be nuts! Actually, I was wrong a second ago. Keep ackin’ all cray cray!” she laughed, as she launched herself off the bed towards the bathroom.
“Hey, I always go first!” called Dipper, lifting his head from the bed.
“Snooze you lose, pal!” Mabel retorted, then quickly closed and locked the bathroom door before Dipper could even get off the bed.

Dipper had a problem. A “hard” problem. His problem was the degree to which his penis was erect, and that degree was a high number.
Mabel had no idea what that tickling match had done to Dipper. Having a girl, even one’s sister, grab a boy all over his body, then drape her body over him to hold him down while she digs her fingers into his ribs and stomach, is a sure-fire recipe for a hard-on. Dipper hadn’t gotten up after his surrender not because he was tired out: he simply didn’t want Mabel to see his erection.
Mornings were problematic for Dipper, and his attempts to tame his occasionally unruly organ. He would always wake with a partial to full-blown erection, but it also usually calmed down shortly afterwards so he could avoid having anyone, particularly Mabel, see it. But if it didn’t go down, he had found that the one way to make it go down was to force a bladder full of urine through it. This is a somewhat long, actually painful process for the male of the species, and just getting the stream going can require patience and supreme effort, but the end result is certainly going to be a relaxed, soft penis.
Of course, he knew the other way to make it go down, and that was to have an orgasm. But that took time and concentration, and certainly it took some privacy.
Dipper found himself with no way to perform either action. The door to the only toilet available to pee into was now locked with his sister inside, and he couldn’t exactly just start tugging himself when she might come out of the bathroom at any time.
He had no choice but to tough it out until she came out of the bathroom. He sighed and tried to think un-sexy thoughts.

Inside the bathroom, Mabel had stripped to step into the shower, but paused to appraise herself in the mirror. She had a healthy body, and a healthy body image. She knew she didn’t have to look like a supermodel to be pretty, and she was happy with what she saw.
Mostly happy. She did wish that her body would hurry up and grow some breasts, for pete’s sake! Mabel wasn’t flat as a board, but she was far from “endowed”. The one minor advantage of having small breasts is that they don’t really require a bra to support them, and Mabel rarely wore one. Of course, a bra can help hide nipples from peeking through a thin fabric top, and Mabel’s solution to that was easy: she just continued her long-standing tradition of wearing big and baggy sweaters over a tight t-shirt. What had been a goofy fashion statement as a tween, had become a practical solution geared for comfort and modesty. Oh, and still a goofy fashion statement, that was a plus!
Still, she was glad to not be too hung up on her appearance. After fourteen years, she thought to herself, she was doing just fine. Some boy would appreciate her very well, thank you very much!
Some boy.
Wait, what boy? She thought to herself. Who’s going to appreciate me? Well, my boyfriend! Then who’s going to be my boyfriend? Who do I want to be my boyfriend? Mabel was genuinely confused, and she had to pause to consider this.
It dawned on Mabel that she had no prospects for her next boyfriend. And wait a minute, when was the last time there had been a prospect? Why had she not noticed that she hadn’t had a prospect in, how long had it been, anyways? She always had prospects!
She had been boy-crazy for years, long before boys her age would ever consider wanting to be a boyfriend to anyone. A romantic at heart, and impulsive, she vividly remembered being infatuated with endless numbers of boys, and had instantly “fallen in love” over a half-dozen times the last summer alone. Mabel sure remembered that it had been easy, maybe too easy, for that twelve-year-old to just slobber over a new target of her affections. She was now fourteen, and she realized that she didn’t do that any longer. When had that stopped? It seemed to her it might have been late last summer, or perhaps the beginning of the school year. She couldn’t picture a single boy at her school in Piedmont that caused her heart to lunge the way seemingly countless boys used to be able to do.
But it’s not because I don’t want a boyfriend, she thought. I’m almost desperate to have a boyfriend. I just want the right boyfriend. Yet I apparently have no candidates, where as a pre-teen I targeted them left, right, and center! WTF? This is too weird!
She wracked her brain, trying to come up with some reason for this change. Her thoughts were interrupted by Dipper’s knock on the bathroom door.
“Mabel? Are you getting ready or not? I need to get in there!” Dipper sounded like he was in a bit of pain. He probably needed to pee.
“I’m just getting in the shower. Can you hold it for a bit?” Mabel replied through the door. Dipper groaned in response. “Thanks, Dip!” Mabel called, as she stepped into the tub and pulled the curtain.
After getting the water to the right temperature, Mabel relaxed under the feel of the flowing water over her body. It felt wonderful, as there was much higher water pressure here than at the Mystery Shack. The soothing force of the water on her back and neck relaxed her, and she unconsciously reached for her nipples and pinched them. She almost jumped, they were so sensitive. Now she remembered how horny she was the previous night, and how she wasn’t able to masturbate to relieve the stress.
Mabel’s left hand remained on her left breast, while she slid her right hand down over her stomach to her vaginal area. She lightly caressed both labia and began to rub her clitoris. She had discovered masturbation on her own late last year, and for a short while she thought there was something wrong with her. And even though she now knew that it was completely normal, she still felt odd about it sometimes. Like how when she fantasized while pleasuring herself, she never pictured an actual boy or man with her. Instead, she pictured only an embodiment of the emotions that were her triggers for her arousal: a person whose reality was not important, only that this was a guy that could make her feel attractive, special and loved. That was kind of weird, she thought, since she knew other girls who masturbated usually pictured themselves with hunky movie stars or pop singers.
This lack of a face to her fantasy reminded Mabel of her lack of any knowledge of a boy, any boy, to possibly be her boyfriend. Dipper had interrupted her thoughts, and now as she gently rubbed herself, she wanted to get back to that topic.
Surely, she thought, there must be some boy at school who would make me drool over him. She ran down the names in her head of her classmates the previous year, looking for one who sparked her romantic interest. Aiden? Way creepy. Brock? Pig (and not in an adorable Waddles way). Gabe? Too boring. Jeffrey? Yeah.. No. Just No. Jose? Obviously gay. Who else? What about Devon? Isiah? Greg? Sandy? Ezra? Anthony? Dipper?
Wait… Dipper?
Mabel gasped. Dipper? Why on earth would she come up with Dipper’s name? She was obviously not concentrating on her task, because she was trying to think of boys that made her want to make them her boyfriend. It would make no sense to think of Dipper, he’s her brother!
As one part of Mabel’s brain finished that thought, another part was making the realization that her hands had just started following new orders. Her left fingers were pinching her hard nipple with greater force. Her right fingers were rubbing her clitoris faster and harder.
Then there was a new realization. Mabel’s masturbation fantasy, the faceless embodiment of her emotion, had suddenly coalesced into a clear picture, and she saw that it was her twin brother Dipper! In her mind’s eye, it was now Dipper’s mouth on her breast, and it was his fingers probing deep inside her. She was rocked with the understanding that Dipper was, in fact, exactly the kind of boy she dreamed of in her sexual fantasies. Not just the kind of boy, he was the boy she fantasized about! Why had she never seen this before? Dipper was the boy she had wanted to be her boyfriend! Dipper was the one who aroused her so much! Dipper, who she knew had always protected her and loved her. She loved him! She loved him!! She love loved him!! Oh my God! Oh my God Oh my God OhmyGodOhmyGod….
Mabel was entirely unprepared as the most massive climax she had ever felt suddenly crashed over her like an avalanche. She almost collapsed in the shower, but managed to lean against the wall as she continued to keep rubbing, caressing, and pinching herself, not wanting the feeling to ever end. Wave after wave of pleasure washed over her, fueled by the knowledge that only one boy could ever make her feel this way, and it was Dipper.
Eventually, though, the moment passed. Mabel found herself sitting on the floor of the tub, pelted by the water from the showerhead. She struggled back to her feet, knowing she had been in the shower a long time, but not knowing how long. As she washed her hair, she remembered Dipper was right in the next room, and had been waiting for her to get out of the bathroom. Poor Dip! She shut off the water and stepped out, calling to Dipper that she would be out just as soon as she could. She’d just have to deal with these new feelings after getting out of the bathroom.
As she reached for a towel, she realized that her memory was missing more information than just how much time had passed. Also missing was any knowledge of sound while she was in the throes of her orgasms. Oh God, she wondered frantically to herself. How much noise did I make while I was in there? And, I wonder if Dipper heard me?

Had Mabel actually asked those questions aloud, Dipper would have been able to answer them. To the second question, yes, Dipper definitely heard Mabel. And as for the first question, the answer would be “quite a lot, actually.”
After Mabel finally started the shower, Dipper had sat back down on his bed. Time was taking care of his “problem”, and he was now only half hard. But now he did really need to pee, and Mabel was taking her sweet time.
Faintly through the bathroom door, Dipper heard Mabel groan. He thought it sounded like pain. Instinctively, Dipper was on his feet. He had listened to his instincts before, and they always called him to be ready to act to help his sister. In a few seconds he was at the door, knuckles raised to pound the door and ask Mabel if she was okay.
Before he could strike the door, Mabel made another noise: a sharp, short intake of breath, followed by another moan, louder than before. Dipper could plainly hear it over the sound of the water in shower. His instinct screamed at him louder, demanding he take action for his sister. But a conclusion about the sound had just been made in his brain, interrupting his gut reaction. His conclusion was that Mabel was not, in fact, in any pain at all.
To understand how Dipper reached this conclusion, one must understand Dipper himself. He was very much like any other young teenage boy, in some ways. One of those ways was that Dipper, like most boys, was attracted to pornography. Looking at pictures of naked women and reading stories of sex has been a standard part of growing up as a boy for decades. But Dipper hadn’t seen all that much by this point in his life. He didn’t have friends cool enough to have access to printed magazines or books, and Dipper was smart enough to not want to have possession of hard copy anyways.
Dipper knew the better solution: the Internet. It was a perfect porn distribution tool, and he had figured out the purpose of the web browser’s “incognito mode” a long time ago. All he lacked was an abundance of opportunity. Grunkle Stan had no Internet connection at all at the Shack, and at his home in California his parents had put the family’s PC (the only one the twins were allowed to use) out in the living room. Still, Dipper had gotten good at being able to steal a quick look at some of his favorite material, then quickly destroy the evidence with a fast ALT+F4 when anyone might be about to enter the room.
Only once had he managed to find himself alone in the house for enough time to watch a porno movie. It was only about twenty minutes before he heard his mom’s car in the driveway, but it certainly was enough to prove to him that actual video and audio of explicit sexual foreplay and intercourse was a much stronger stimulant than photos or stories. He had watched it only the one time, but the details were burned permanently into his memory.
One of those details was the sounds the young woman in the movie was making, over the course of most of the twenty minutes Dipper had watched. And the noises he was now hearing from Mabel in the bathroom sounded a lot like that!
Dipper gaped at the door. Mabel? Was she….. turned on? Another gasp and moan escaped through the bathroom door. Wow, thought Dipper. He hadn’t really considered that girls masturbated like boys, or that Mabel could ever be masturbating, like he did. Was she really getting herself off in there right now?
Conveniently, Mabel answered his unspoken question. The next sound her brother heard was a very sharp intake of breath and an unmistakably clear, urgent whisper of “Yeeessssssssssssss!!!!!!!”
Dipper was frozen to the spot, unable to stop listening to his sister. His need to empty his bladder was completely forgotten. And his erection was back to full strength.
Obliquely, he realized he wasn’t bothered by the fact it was Mabel that was causing these erotic feelings in him. He supposed she was very pretty, if he was any judge, and of course he liked his sister. Well, he loved his sister, of course, and, well, but…. he wasn’t supposed to feel horny about her. But he quickly guessed it wasn’t hurting anyone for him to just fantasize about her now, especially since she was providing him with a private recital.
If he was thinking about Mabel, Dipper started wondering about what guy Mabel was thinking about in there? No, he pushed that consideration away, as the thought provoked a quick feeling that was decidedly not arousing, so he didn’t want it. Whoever he was, Dipper didn’t want to know him. As he forced it from his mind, he still idly examined the emotion. It was… anger? Loneliness? No, neither of those, but it was definitely not a pleasurable feeling. Then it was forgotten.
Suddenly, a whole new class of noises erupted from the bathroom. Dipper could hear accelerated gasping, followed by a quick succession of “ohmygod”s, and then almost a keening wail. Oh man, he thought, is she still alright? Mabel repeated the noise again, then gradually transitioned to a long series of heavy gasping, so heavy that it sounded like she was sobbing. It seemed like it was going on forever.
This performance was almost too much for Dipper. His arousal was virtually total, his penis as hard as he could imagine. If he even touched or arranged himself, he didn’t think he could stop his orgasm if his life depended on it. All he could do was slowly ease his way back to the nearest bed, and sit perfectly still until Mabel let him into the bathroom. Mabel’s ecstatic noises continued to emanate through the door. Dipper’s tension was actually painful.

Mabel hadn’t brought in one of the hotel’s big housecoats into the bathroom with her. She’d have to be satisfied with wrapping herself in a large towel so that Dipper could get in.
Before Mabel opened the door, she knew she didn’t want to look at her brother. She knew that if he heard her, he’d probably have something to say, or at least give her a knowing leer. Under the best of circumstances, she might be able to handle that (but it would still be really embarrassing). But she was also dealing with her new-found knowledge that this same boy who might tease her was also the boy who made her feel so intensely horny, and safe, and …. loved! And that he was her brother. And that they were about to spend the entire day together. There was no doubt that she would shatter if he teased her right now.
She quickly opened the door and marched straight past Dipper, who was sitting on Mabel’s bed with his head down, elbows on his knees. He glanced up, muttered “thanks,” and immediately entered the bathroom, locking the door behind him.
Well, that was okay, she thought. At worst, he knows what happened in there, and is choosing to be polite. And at best, I wasn’t noisy at all, and he really just needs to pee, really really badly. I can deal with that!
As she pulled on a bathrobe and towelled her hair dry with a second towel, Mabel started examining the situation, and began to despair over how any of this could turn out. For starters, Dipper would never reciprocate her feelings. She knew he loved her, and had proven that over and over, but he couldn’t be in love with her! He thought of her as his silly sister! Was she doomed to living through the remainder of her youth, so close to the source of the most intense feelings of her life, yet forced to stay silent?
Then she considered that Dipper may not even “get” any of how she felt. She knew he’d had crushes on girls before, but she’d never seen him do or say anything remotely sexual. But she had seen him quickly closing programs down on the computer back at home, just as she would be walking in the room. It might have been a porno web site. Mabel knew a lot about what boys go through when they start to become men, when she (unwillingly) received a full education on the subject from Grunkle Stan. Mabel had hit puberty already: her first menstruation had arrived a few months ago, just before school let out. Boys were supposed to start producing sperm at some point. She wondered if Dipper had yet reached that milestone.

A towel! Dipper agonized over the last thing he saw before he entered the bathroom. She was wearing only a towel!
After he locked the door, Dipper could hardly contain himself. Carefully, but very quickly, he got out of his shirt and shorts and stepped into the tub, not even managing to turn on the shower. Three strokes, in under two seconds, and he was past the point of no return. He continued pulling furiously on his penis.
His whole body shuddered with the intensity of the climax, every muscle tensed. He involuntarily held his breath as his testicles struggled to push their supply of semen out through his penis, made more difficult because of his full bladder. Still, he managed to keep up the stimulation.
When the first stream finally erupted, spraying the wall of the tub stall, Dipper almost screamed with pleasure mixed with pain. Almost. A tiny part of his brain remained vigilant, demanding that Mabel could not know about this! He knew he could never explain to her why he could be so turned on by her and her sounds of pleasure. She would hate him! No, he had to somehow keep silent.
And he managed it. Somehow, hyperventilating with his mouth wide and making as little noise as possible, he was able to quietly ride out an orgasm that was by far the strongest of his short sexual life.

Both Dipper and Mabel managed to pull themselves together. They both were hiding feelings that they couldn’t fully explain, and even if they could, they were already running late.
Dipper had taken his shower and sprayed down the walls of the tub stall, now feeling a bit guilty over how he had dirty thoughts about his sister, but only a bit. He was also a bit down because of the fact that some guy out there was awfully lucky, that he (whoever he was) had what it took to make his sister feel so aroused, and found he was actually jealous (Dipper successfully identified the emotion that had eluded him earlier). Why would he be jealous? That was dumb. But could Mabel have actually been trying to make him jealous? Surely she knew she could be heard through the door, what with the sheer decibel level she produced. She must have intended him to hear her, but why? Then she paraded around in just a towel. It was too uncomfortable to process, and he just wanted to pretend it had never happened, at least for now.
Mabel returned to the bathroom to finish getting dressed and to fix her hair, silently pondering her newly identified feelings for Dipper. The feelings of love confused her. She had been taught, of course, that a girl can’t feel that way about a brother. Not shouldn’t feel that way, can’t feel that way! But she most assuredly did feel that way! So what did that mean? Was she a degenerate? No, she was certain that she wasn’t. But she was sure that her feelings were taboo, that no one would be supportive of her feelings. This was going to be difficult to deal with.
Soon they had completed their individual tasks and were ready to leave, and met at the door. They both actually looked at each other for the first time since their impromptu wrestling match.
Mabel was relieved to find herself looking upon “her brother” again. Dipper looked completely normal in his customary t-shirt, vest, and cargo shorts, and of course his trusty pine tree ball cap. She still didn’t know how much he heard of what she experienced in the bathroom, but he was giving no indication he had heard anything at all. She found she could put her feelings for him on hold for now, and decided she was ready to just have a great day with her dorky brother. The thought of the fun day to come brought a big smile to her face.
That smile was exactly what Dipper needed to see. He knew how genuine it was, and he couldn’t help but smile back. He was so much more relaxed after getting himself off in the shower. Gone for the moment was the sexy girl that seemed to be trying to play on his emotions for some reason, and back was his favorite goofball in the world, complete with “beaker and test tube”-themed baggy sweater. What a great sister!
He opened the door to the hallway. “C’mon, let get going,” he said, nodding to the open door.
“Righto, old chap!” cried Mabel in a terrible British accent as Dipper snapped closed the door to their room. “Get it? Old? ‘Cause it’s your …. birthday? Boop!” Mabel poked her finger into Dipper’s cheek as they strolled down the corridor. “Oh, me too! Boop!” Mabel poked herself in the cheek, then poked the Down button as they arrived at the elevators. “Boop!”
Dipper rolled his eyes and smiled again.
The twins were off to have the best birthday ever!
- 2
- 3
- 4
You need to be logged in to leave a review for this story.You need to be logged in to leave a review for this story.
Report Story

Fistbump (a Pinecest story)