Dipper was horny. So was Mabel, but that wasn't new. Considering that they are still going through puberty. Mabel had always peeked thought the cracked door, watching Dipper jack off to pornography. This was expected, since he's a teenage boy. But his twin sister watching him? She had a guilt conscious, but she was EXTRA wet this time. it may have been a perfect time since Stan and Soos left to give the tourists a view. So there they were, seperated between a slightly open door, although dipper was facing his computer screen and not Mabel.

Mabel slid her fingers down to her sensitive spot, as Dipper slid his growing hand to his soon-to-be hard cock. As he started, so did Mabel. "What am i doing? He's my fucking brotheR. My TWIN brother. Oh god." But she ignored it, as she heard slight moans froms Dipper's mouth. She couldn't help but drop to her knees quietly, and insert a finger inside herself. They were both reaching their climax. And finally, they released. Dipper may have heard Mabel moan, because he opened the door to find a satisfied Mabel resting her head on the wall.

"Mabel?! What are you doing?!" She frantically pulled her fingers out of her wet panties and backed away.

"Dipper! I... I...-"

"Were you... Masturbating...?"

Mabel spoke broken English. Then something strange happened. Her embarrassment turned into rage, and she stormed downstairs, leaving a confused Dipper. He was confused, but still turned on. Thinking about the fact that his hot sister was fingering herself to him. His courage to go down and speak to her was growing, as was his erection.

"Mabel.. Please. i... It's fine... I think... About us like that too..."

mabel didn't know how to feel. She was still horny. She wanted Dipper otherwise.

dipper moved closer to her, as she was sitting on the couch with her arms folded.

"D-don't be mad, M-mab..." He ran his fingers up cross her thigh, slowly. His mind filled with dirty thoughts. "Why do i want this so badly?" He thought to himself.

mabel loosened up eventually, then took his hands and placed them both on her developing boobs. Dipper turned red. He began rubbing her hard nipples through her tight shirt, which she wore around Dipper ALL the time. Mabel let out tiny squeaks, and succeeded in turning Dipper on even more. Out of her remaining rage, she rammed her lips into her brother's. They couldn't take it anymore. They wanted each other so badly. dipper fell back into the couch, with Mabel on top, furiously kissing. Mabel ran her hands through Dipper's fluffy brown hair, and Dipper squeezed her butt cheecks a bit. The kiss was wet, passionate, and straight up sexy. The lips on top of each other's, all out of lust.

"Dipper, i want you. i always have. Please."

dipper looked puzzled at first, staring into her sparkling eyes before giving her a short kiss, then replying, "I want you too. Let's do it. Hard."

"Oh yes." mabel winked.

they moved to the floor for more space, as they started undressing each other. Mabel took off Dipper's shirt as he ripped off Mabel's tight shirt. he REALLY wanted this.

Mabel got down on her knees and said' "Stand up." Dipper obeyed. she rushed to take off his belt, then his pants, revealing his stuck out member that was longing to be released. Mabel bit her lips as she looked into Dipper's eyes. "Long and hard. Just how i want it." She tugged down his boxers before sticking his dick in her wet mouth. Dipper started to get lost in this fantasy that was finally coming true. She sucks and sucks, his part going down her throat repeatedly. He didn't want to come imeediately. He wanted to savor this moment. she continued to suck, she would look up at him momentarily as she slowed down, lips playing with the head, then she would stick it down her throat again. He was going to release. "Uh. M-Mabel. YES OH GOD." He came down her, she seemed to grimace a bit, but was happy to swallow every last drop. When she pulled it out, her lips were slippery with come. she teased Dipper a bit because she wanted him to return the favor.

Mabel layed back on the floor as she spread her legs in front of Dipper. She took off her panties that were soaking and tossed them to the side. Dipper did not hesitate to place his face in front of her womanhood. Him breathing on it was enough for her to raise her arms above her. He started licking her up, not missing one spot. She instantly went wild, shifting her lower legs so she squished Dipper's head slightly. He inserted his tounge, which did wonders. She arched her back to him, shutting eyes closed, mouth releasing high moans, making Dipper crazy as well. Dipper grabbed her butt with both hands and lifted her closer to him. Faster and wetter, he licked her clean as she came and shouted out.

they couldn't wait anymore. It was time. right after Mabel came, she flipped around on all fours awaiting Dipper's entrance. "Fuck me. i want to feel you inside me. come on." Moving swiftly, Dipper got on his knees positiong his dick to her vagina. He wanted this badly too, and he couldn't help but push in deep, causing mabel to scream in joy. It didn't hurt her, but she felt a throbbing sensation. "talk filthy to me, baby. God you feel so good." Dipper wanted her dirty words. "Yes, master. Just fuck it." he squeezed her ass cheeks as he moved her back and forth, increasing speed with every thrust. mabel wished she had something to grab onto, as she loved the sensation so much. "I fucking love your cock inside me. uh. yes. fuck yes." She was so wet, and this helped Dipper move faster. Sweat began to form on both of them, but it didn't matter. In and out and in and out, dipper watched his wet cock entering and exiting his sister. "Baby yes, fuck me harder." if that was even possible. He had a slight moment of realization that he was fucking his twin so hard and fast that she was dripping onto the floor, but it faded as their moans were drowning out everything. The floor was thumping, the sound her ass bumping into his Lower half whenever he thrusted, Dipper even gave her a hard slap on it causing Mabel to shout out with excitement. They were both close. Grunts becoming high pitched, closer, and closer, then finally they released. Dipper came inside Mabel, shooting up inside her, and she fell to the floor, exhausted. He pulled his slippery cock out and layed on top of her, his chest to her back. "let's do it again." Mabel said.