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Horny Ghosts	By : PineWreths Category: +G through L > Gravity Falls Views: 10662 -:- Recommendations : 0 -:- Currently Reading : 0
Disclaimer: I do not own Gravity Falls, nor the characters from it. I do not make any money from the writing of this story.

Chapter List
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Dipper chuckled nervously and coughed as Mabel began rooting through a rack of clothing. They’d just ran into Victoria’s Common Knowledge, the lingerie store that Dipper was only familiar with thanks to a stack of dog-eared magazines and a single, very uncomfortable visit for a gift for Pacifica back when they’d still been dating.
He winced with the memory; The night he’d brought over the gift had been the night words had been exchanged, a glass of wine had been thrown, and Dipper went home single, unopened package under one arm. However, he thought, looking in the direction of his sister as a poltergeist seemingly hummed quietly while flinging bras and teddies aside casually, I think I came out ahead in the end. Hell, if I remember my sister right, she’s about the same dimensions as Pacifica, if a bit more ‘generous’ in the right squeezable places; Maybe a regifting is in order?
Striding over, he guessed where his twins nude, invisible ass was and grabbed. His effort was rewarded by a quickly-strangled squeak as he found his mark, Mabel gently slapping his hand away but reaching over to grab and stroke Little Dipper briefly before going back to the rack.
Dipper had become notably distracted by the attention, and let out a little impatient groan as she turned away. He took a step forward, pushing himself against her while letting out a little growl, but after a quick giggle she said sternly under her voice “Dip! Just…just turn around or something; I want-I want to-Oh, just turn around already!”
He grinned, unseen, as he could tell she was getting flustered in that cute way he loved, but he obliged her; She couldn’t see if he had, but he knew she trusted him to do so, and Dipper personally enjoyed sexy surprises, so he wasn’t complaining either.
Plus, it gave him a chance to look around the rest of the store. There was a lone employee at the far counter near the entrance, but other than that the store was empty. The employee had his nose buried in a book, some kind of romance novel judging from the hairy shirtless scotsman on the cover, and as a result he must have assumed the store was empty. The mall muzak covered Mabel’s rifling through the displays, but after another minute or so, he heard a low “Dip? Dip, where are you?”
He walked towards the sound of her voice, saying “Mabes, I’m over here,” as he got close, and felt the breath go out of him as he bumped heavily into his twin. She fell, giggling as an armful of various lacy bits of clothes went everywhere, and Dipper snickered as well.
Apparently, they must have been louder than they thought, because a second later they heard a confused “Hello? Who is that?” from the counter. Dipper felt his eyes go wide, but Mabel’s giggle went from laughing to mischievous, as she grabbed his arm and then his hand, pulling him after her as she ran with her armful of lingerie.

She had pulled them into one of the empty dressing rooms, pulling the door almost-closed so a passerby wouldn’t see a floating bra and panty set, but not enough to make the employee think someone might still be in there.
Putting a hand on his shoulder, she firmly spun him around, saying “Ok, hold tight and the authentic Mabel-brand fashion show and striptease will begin in a minute.”
Dipper felt his heart surge a bit at the second half, but after a minute of the sounds of struggling and clothing, he could hear a defeated “Uh, little help brobro?”
He turned, and took a second to comprehend what he was seeing. It looked like someone had made a loose ball of yarn out of silk ribbon, and tossed in some lacy black handkerchiefs for effect. After another second of comprehension, he realized what was going on and snickered, earning a disapproving “Huff!” from Mabel. She had somehow managed to put on the strappy outfit upside down, and if Dipper’s guess accurate, she had at least one arm through somewhere that was not an arm hole.
He took pity on his flailing sister, and helped her right the outfit. Before she got it finally situated, she spun him around again, saying “Thanks Dip, but there’s a few finishing touches I can do by myself.”
He turned, and could hear the rustling of paper, and several zipper noises as well as the sound of cloth sliding on skin, before a little timid voice said “Okay, you can look.”
He turned, and felt his heart skip a little, before warming with loving sympathy for his sister. The outfit accentuated the edges of her curves wonderfully, as did the fishnet arm warmers, stockings and black kneehigh boots she’d conjured out of nowhere as well, but he felt barely a twinge of arousal; Evidently, seeing his sister’s soft skin being hugged by the fabric was far more of a turn-on for Dip than seeing it suspended like it was held together for a display on fine strings and wires.
But the surge of sympathy was because he recognized the pose with the way her hips and shoulders must have been positioned; She was feeling self-conscious, unsure of what her brother was going to think or say, and his silence must have clued her in to his tepid response as she sadly let out a little shaky breath.
She started to turn, but Dipper reach out, caught her arm, and pulled her towards him. He had originally done so reassuringly, beginning to say “Aw Mabes, it’s o-” before stopping.
While the invisibility had definitely crimped how much he was being aroused by what he could see, what he could feel was another matter entirely. Feeling his sister’s warm arm under the fishnet, where the curve of her ass met the base of the silk straps when he reached his arm around, that was definitely making Little Dipper’s day.
“Oh,” he said, and he could feel her tense in confusion, but then shimmy up to him and press her body against his as she realized what was going on. “Well, Dipper,” she said teasingly, “What do you think of this one?”
He growled appreciatively, trying to pull her towards him to sit on his lap, and by sheer coincidencehis erect cock as well, but she merely bent over slightly, rubbing herself teasingly along his shaft before standing up and beginning to pull off the outfit.
Again, she had Dipper turn and not peek; It was far harder this time, but he managed, and after a minute more she tapped him on the shoulder again. He turned, letting out an appreciative low whistle; His sister had on a one-piece bathing suit, modest in coverage but risque in the thin, glittery choice of material, her nipples clearly erect underneath the reflective fabric.
He growled again, pulling her over towards him, but when she went to try and turn and squat again to teasingly rub herself along him, Dipper reached over, running a finger along where her crotch had been oh-so-nicely outlined by the swimsuit. She let out a gasp that shivered into a moan, and suddenly she stopped getting up, and sank back down to grind against him, hard, as she let out a growl of her own.
Their lips met, and Dipper enjoyed the sweet vanilla-bean taste as his other hand went to tease one of the excited nipples. She reached down, pulling the fabric to one side, and began rubbing her lips along and around the head of his cock, causing him to groan. He moved his hand to her thigh, and began insistently pulling her down towards him.
Mabel obliged, and he slid into her; Apparently she had been more turned on by this whole affair than Dipper had realized, because after just a minute of gentle rocking and him occasionally raising his hips slowly, he could feel her shudder and come, tensing around him.
Dipper was having a slightly harder time enjoying himself, as the material of the swimsuit, while beautiful and sexy as hell, had slid back to sandpaper itself against the side of Little Dipper. He reached up and pulled the straps off of his twin’s shoulders, and she did the rest, shimmying it down to discard on the other side of the booth, as they sat back down on the cushioned bench.
“Guess we’ll have to try some of these when Mabel is plain-old Visible Mabel,” he said, looking at the stack of lingerie on the opposite bench a few feet away, and he could feel her nod, although she caught herself and responded with a little laugh and a quiet “Yeah, definitely.”
He could feel her freeze along with him, though, when they heard the dressing room door next to them clatter open, along with the employee’s voice shouting “A-HA-uh? Dammit, I could have sworn I heard someone.”
Dip forced his breathing to a crawl as the footsteps approached and the door creaked open. The employee swore, itching his head as he looked around. Dipper could feel his breath catch in his throat in terror as he looked right at them, but then his gaze passed back to the discarded clothes, and he said “Man, I gotta clean up after some damn teens again. This blows.”
Dipper started to let out a slow, whoofed breath, and Mabel did the same, even going so far as to shift and grind a little on him, restoring the erection inside of her that had been softened by fear.
Then the employee turned towards them, hand outstretched.
Dip choked down a whimper of terror, whipping his head around furiously before spotting the lone, guilty neon-teal thong he was unwittingly sitting on top of. There was no way his hand was going to avoid hitting something, and Dipper tensed, as did Mabel, the employee bound to meet them at any second-
“BOO!” His sister leapt off of him, shoving the employee while screaming in his face. The employee responded with a high-pitched shriek, falling and scrabbling backwards in a cloud of lingerie and lace as Mabel laughed and ran past him. Dipper followed soon after, grinning at the shaky voice behind him echoing panickedly “What the fuck? I thought they exorcised all the ghosts and haunted shit!”
The rest of the afternoon was spent mischievously. The twins spent a while in Baskin-Floggins: 21 Flavors of Kink!, the little poorly-lit sex shop over on one end of the mall, and proceeded to lead a pair of employees in little circles around the shop by placing dildo breadcrumb trails around the sets of shelves. He could tell from how she paused that Mabel was eying several of the options hanging from the wall at one point, but he leaned in, running a hand along her suddenly-shivering back as he murmured “If you want the real McCoy, all you need to do is ask.”
She gave a little appreciative murmur back, but then was distracted by an array of glitter pasties and edible body paint before going over to the condom rack to start arranging the packets to form little inspiring messages. Dipper let out a slight disappointed sigh at the lost opportunity, but then moved to help her with the condoms.
They then moved on to Yumberjacks, stealing a few incredibly-hot-and-fresh fries while Dipper quietly whimpered about the idea of boiling oil being that close to his unguarded junk, a splash away from utter tragedy. Mabel was about to start rearranging letters on the menu sign when the PA crackled on across the mall. “The time is now 8:45 PM. The Gravity Falls Mall will be closing in 15 minutes.”
His hand in hers, he could feel his sister shrug, and say in a slightly dejected voice “Well, ready to go home Dippingsauce?” He grinned, but tugged her slightly away from the exit doors they had started heading towards. “Not yet Mabes, not yet.”

Dipper had to admit, he was putting on far more bravado for his sister than he felt when he pulled her up alongside him, both of them standing on the raised, empty set of benches overlooking the escalators and the main mall entrance. People were streaming out by the dozens, and if Dipper had been visible, he was sure he would have caught fire and died of embarrassment.
But I’m not visible, now am I? He pulled Mabel close for a kiss, his hand running and teasing along her side as it descended, running along her hip, reaching behind to give her ass a quick playful squeeze, before drifting under to run a finger along her lips, almost tickling them.
His sister was tense at first, but after a minute the anxiety began to wear away, replaced by excitement and passion. She returned the kiss, one hand running along his sparse-but-still-there chest hair while the other reached down to give Little Dipper some additional stimulation that he did not need, but absolutely did not mind whatsoever.
She lifted a leg up and Dip responded by reaching underneath to hoist her up, where she slid onto him with only a little maneuvering around. He started to lose his balance, but they shared a little laugh as he caught himself, locking his mouth on hers for another kiss. Mabel had starfished around him with her limbs, and the weight was finally getting to Dipper, so he started to try and shift towards the bench.
The sensation wasn’t doing his stamina any favors, however, but then his twin climbed off unexpectedly. Dip could still hear her panting as she moved slightly away from him, towards the bench. She murmured for him to come over, her voice desperate and flooded with needing lust. He followed the sound, and his outreached hands felt the hot, slightly-sweaty skin of her back, tracing down to the top of her butt, and maneuvering himself, he slowly, almost lazily pushed into his sister from behind.
Mabel let out a little “Meep!” of pleasure, shivering and tightening on his cock, and as Dipper began to thrust into her harder and faster, he could feel her shudder and clench on him, arching her back upwards and grabbing his hands, directing one to grab and play with her breast as the other seemed to be trying to grab his hip to pull her deeper onto him.
She began pounding her hips downwards, the bench making a little quiet creaking noise that caused Dipper to be suddenly grateful that the mall was almost empty now, the muzak still blaring out over any errant sounds they made. His sister had released Dip’s hands, as they roamed around her chest and reached down to toy her clit and run wet fingers up around her nipples and to her suckling mouth.
Then, with another building groan of pleasure, Mabel grabbed his hips with her hands like before, and her pace slowed as he felt her clench in another orgasm, a shuddering happy “Aw-oh-ohgodDip-oh”moaned out. She slowed to rest on him, a final happy aftershock sending her brother over the edge, and he came as well with an audible, drawn-out groan. Mabel let out an appreciative hum of pleasure at the sensation, drawing back to give him a kiss, before finally breaking apart as they saw the last handful of visitors approaching the door below them.
“As much fun as I’m having, I’d rather not be stuck here overnight.” Dipper nodded at her words, and they broke apart, giggling quietly as they ran down the frozen escalators and shadowed the people leaving out the automatic doors.
Dipper found Mabel’s hand, and they began walking towards the end of the lake they’d stashed their clothes in, when there was a rumble of thunder, and a few fat raindrops began to fall.

FIN.
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Horny Ghosts