"She may complain about her butt, but she really just sounds like a slut," you rhyme off. The wand seems to like that.
"No. I'm just too fat!" Your sister exclaims. Her flesh quivers as she pats down her wide hips. She can't help herself now, unwilling to stop her hands running up and down her meaty legs. Fingers stink deep into the soft flesh as she pokes and prods the endless, thicc curves. You listen to her moan in both arousal and anguish. "So big. There has to be somewhere I can rest my fat ass!" Leaning forward as far she could, the bottom heavy woman grunts with the effort of lifting her over sized rump off the couch.
Just watching her walk was a treat. Your rock hard from just the sight of how slow and heavy she is now. You watch her callipygian cheeks wobble and shake as she waddles away. You follow, hypnotized by your step sisters gigantic booty. The girl can't even walk straight with all that meat on her legs and the two yoga balls worth of fat behind her. Her brood mare hips role with every step and her legs struggle to maneuver around her fluffy thighs. Her cheeks sway and collide in a carnal display of physics. She leans forward, overladen by all that junk in her trunk. Back arched and hips rotated, the full figured young woman couldn't help but swing her hips and stick her butt out.
Things only get better with the first obstacle. As you near her room you began sizing up the doorway. Your mental math checks out. You've made your sister so ridiculously big that she is now wider than a door frame. You watch the inevitable collision. 'Phwumph'. Wide flank grab on, locked with the sides of the frame and halting your big sister's progress.
"sigh. They make these doors small on purpose. They just want to see my big. Fat. Booty get stuck!" She complains, smacking her bum to emphasize her words.
You nearly cream your pants watching her globular cheeks violently bounce and quiver with every strike. Eventually she gets to work squeezing her bulk through the door. She braces her hands against the door frame for leverage, rocking her hips and wiggling her fluffy thighs. You can't hold back any longer and decide to giver her a hand. In your own way of course. You grab hold of her flanks, feeling her soft flesh under your hands. You jiggle and wobble her fat cheeks, marveling at how they bounce off each other. You push and prod but your hands are not enough. You press yourself against her back and feel her butt being squeezed between you. You thrust your pelvis, pushing her and humping her in equal measure. Amazingly the spell holds strong and the flustered woman never seems to notice. The wooden frame creeks and the girl grunts as you pound away. Everything is building to a climax and something has to give. Her mounds of meat are inching their way through, but the bulge of your engorged dick is nestled perfectly between her cheeks. Finally, the seal is broken. With one final push your sister breaks free and nearly loses her balance. Your cock explodes and gushes with juices, your crotch turning dark as cum floods your underwear. You've never came so hard in your life and your pants are soaked with jism.
You rid yourself of the soiled clothing. Even after that leg shaking orgasm you're still hard and twitching for another go. There's something thrilling about stripping down. About being stark naked with your engorged cock just a few feet away from your super hot step sister and no one can see. You imagine this is what streaking feels like; a strange mixture of both powerful yet exposed.
Your big sister had managed to totter over to the bed. She slowly lifts one of her legs onto the mattress. A twist of the hips shifts the weight over the bed. With one final grunt of effort, she simply drops her bottom heavy frame onto the bed with all the grace of a fat cow.
"Finally, somewhere I can actually rest. I'm going to need a bigger bed soon." your sister complains, patting her own hindquarters in amazement.
She settles down for a long session of internet and texting. Laying on her side you could truly appreciate just how disproportionate you had made her. Her enormous hips loomed massive over her like some mountain of fertility. Her sleek and slim body looked absolutely tiny compared to all the padding piled up behind her.
You climb onto the bed.
You lunge forward, groping her ass with wild abandon. You squeeze the globes of fat and feel your fingers sink deep into the squishy flesh. You've never felt anything so soft and luxurious. Yet no matter how much you kneed her supple flesh, it would immediately bounce back to their perky and round shape. It's like a drug, you need to touch more. With such an expanse of skin before you that should not be difficult, that overstuffed rump sat nearly as tall as you. You latch on, hugging and burying your face in her pillowy flesh. You wrap your arms around one of her squishy cheeks while the other fills your lap, straddled between your legs. you've never felt something so divine as your naked body pressed against her soft, pliant body. There is much for your cock to explore; the deep cleft of her thick thighs and bubbly butt, the endless cleavage of her massive cheeks, the hot space between your two bodies. Through squirming and thrusting, your fetish fuel of a big sister remains Blissfully ignorant as you wildly hump her. Your whole body seizes as a nerve frying orgasm runs through your muscles. Your throbbing meat pulses with pleasure as your cock spurts out endless volleys of jism. You feel the slimy fluids flood the space between your sandwiched bodies. Your orgasm finally relents and you collapse, draped and collapsed over the bounteous of booty.
Eventually you rise from your stupor and...