I never planned on wearing my sister's panties that night, but there they were, stretched tight over my cock, the silky black lace digging into my ass while I stood in front of the mirror. My sister, Lena, was supposed to be out with her boyfriend, but she came home early and caught me red-handed, or rather, panty-handed.
"Fuck, Jake," she said, leaning against the doorway, arms crossed under her tits. "Those are mine. And they look way too good on you."
My face burned, but my dick twitched harder. "Lena, I… shit, I didn't mean—"
She stepped in and shut the door. "Don't stop. Turn around. Let me see how that thong splits your ass."
I did it, slow, feeling the fabric ride up between my cheeks. My balls were already tight, pre-cum soaking the front. Lena walked right up behind me and grabbed my hips, grinding her crotch against my lace-covered ass.
"You've been stealing my panties for months, haven't you?" she whispered, voice low and filthy. "Jerking off in them, thinking about me catching you."
"Yeah," I admitted, raw and direct. "I stroke my cock in your thongs and imagine you watching."
She reached around and squeezed my shaft through the lace. "Then tonight you're going to fuck me while you wear them. No pulling out. No pretending this isn't exactly what you wanted."
Lena pushed me onto the bed face-down, yanked the thong aside just enough to expose my hole, and spit on it. She worked one finger in, then two, stretching me while she talked dirty.
"Look at you, big brother, all dressed up like a slut in my underwear. Bet you've dreamed about me pegging this ass or riding your cock while you moan in panties."
She stripped fast, climbed on, and sank down on my dick without warning. Her pussy was soaked, hot, gripping me like a fist. The lace rubbed against her clit every time she bounced, and the wet sounds filled the room.
"Harder," she ordered. "Fuck me like you fuck your fist in my stolen thongs."
I grabbed her hips and slammed up into her, the thong still framing my cock as it disappeared inside her. Every thrust made the fabric tug at my balls. Lena leaned down, bit my neck, and whispered, "Tell me how it feels wearing my panties while you breed me."
"Feels fucking dirty," I grunted. "Feels like I'm your little crossdressing whore."
She came first, clenching around me, soaking the lace even more. I flipped her onto her back, kept the thong on, and drove into her until I unloaded deep, pulse after pulse, the panties stretched and ruined between us.
We didn't stop there. She made me keep them on while she sucked me hard again, licking our mixed cum off the lace. Then she rode my face, grinding her pussy on my mouth while she fingered my ass through the thong's thin strip.
By morning the panties were shredded, soaked, and we were both wrecked. Lena kissed me slow, tasting like sex and sweat.
"Next time," she said, "you wear the matching bra too."
I just nodded, already hard again at the thought.
