Kim wants to sit on Becky's lap

By: Cheese111

"How's about I take a seat in your lap. I bet he'll only be satisfied with two big butts worth of weight crushing him flat." She twirls around and shows her bare ass off to Becky, who just gives a lewd smile in return.

"You could just take a seat... Or you could take a 'seat'. She rubbed her shaft to full mast, giving Kim a suggestive look. Your sister didn't even seem to flinch when presented with the impressive cock. She had one even bigger herself, but it wasn't often she'd taken one up the back door. It made her kind of giddy to experience it. Slowly she stepped closer, tempting Becky to grab her sides and pull her into fucking range already. Your girlfriend gasped, feeling her shaft get caressed by those luscious buns.

So often she'd dreamt about finally revealing the truth to Will. He would react with joy and they'd spent so much time pounding eachother everyone at school would be jealous. She closed her eyes and imagined it was him sliding down her cock. The tight tunnel clenched a few times, squeezing her rigid shaft as it sank in deeper. Both of them moaned loudly as Kim settled herself in Becky's lap, feeling the full length of her huge dick throbbing inside of her.

From your compressed hell you could vaguely hear the moaning overhead. Without warning the pressure started mounting again. Had Becky been holding back on you all this time? Was there even more to this torment? What little movement you were capable of before was now reduced to nothing. The torturous weight made it hard to breathe, threatening to suffocate you beneath the avalanche of ass. Even with all of your sister's help, you feared you weren't durable enough to survive this kind of onslaught. Hopefully she'd save you before this went too far. As though your prayers were heard the weight lessened, only to deliver a merciless hammerblow right after.

"Oh. Yes. Keep going." Becky's voice was haggard, worn from pleasure. Kim was gently bouncing up and down in her lap, her ass doing a legendary job of stimulating that huge cock. She couldn't hold back much longer. She grabbed Kim's hips and pulled them into her lap, holding her still as she blew her load deep inside of her colon. Kim's body shuddered up and down, the intensity of Becky's orgasm leading her to echo it. Several thick ropes of cum flew across the room. Finally things settled a little, the potent heat slowly dissipating as they relaxed. Becky was still buried deep inside of her and her shaft barely shrunk as it wilted. It felt good in there.

After a few minutes of recovery Kim got up, her ass making a nasty slurping sound as Becky's shaft was freed from it. The floppy column dropped into her lap and your sister turned around to reveal the biggest of grins. "Hmmm, I wonder how little Willy's holding up."

Becky giggled and got up from the bed. She'd stopped paying attention to you when the sex began and now it was time to see how tough her boyfriend really is. She wouldn't expect you to have any trouble with this, but she didn't really have a frame of reference for how much a tiny guy can handle. She was pretty confident in asserting that you will have loved being sat on as much as she loved fucking your sister. Even the mere idea of turning this relationship into a threesome sent a wave of excitement through her. Although with you being fun-sized, it felt less like a threesome and more a very kinky extra to a relationship with Kim. She turned around to look at you, Kim leaning in over her shoulder to sneak in a glance as well.