Yes- she actually does!

It's a long moment of silence later, but your sister pulls her arms from your balls and then out the sleeves of her shirt, unhooking her bra after that to ceremoniously undress before you. "Not bad actually, but if you do cum in me and I get pregnant, I'll tell and you'll pay child support." She answers flatly... even so, you're impressed, but you slightly dread that you will lose your balls for real in a short time.

Your sister continues to undress: her body is quite good- a slender but wide-hipped build, with the thickness of muscle about her thighs and barely-visible, smooth abs. She has wavy brown hair in a ponytail and two green eyes that often glint with the madness you have just witnessed. Her face... is average: her cheekbones are a bit too large, her lips are very thin and her brows are thick, but the bust and butt of her svelte body definitely makes up for it.

She pries her panties off her crotch. The fantasy of crushing your balls has made her super wet!

She unceremoniously climbs atop you and twists around, giving you a view of her pert, broad asscheeks. "That's fine..." You answer; if you came in her, you'd be in trouble, but if you didn't- you'd have no chance to reproduce. You aren't sure what to do...

Your sister pulls-off your underwear, finally leaving you naked and letting your fat seven inch dick flop free. "And I'm going to squeeze them as I do this. When you cum, I crush." She declares with a glare over one shoulder at you...

It's a cold, determined look.