The bus was packed tight that Friday night, bodies pressed together in the humid summer heat. I stood behind my sister Lena, my chest against her back, my cock already half-hard from the way her round ass brushed my thighs every time the vehicle lurched. She was twenty-two, same as me, both of us home from college for the weekend. Mom and Dad thought we were taking the late bus together for safety. They had no idea what safety really meant on a crowded ride like this.
Lena wore a thin sundress, no bra, the fabric clinging to her heavy tits. I knew she was bare underneath because I'd watched her get dressed. When the bus hit a pothole and everyone swayed, I let my hand slide down and cup her ass. She stiffened but didn't pull away. My fingers squeezed, digging into the soft flesh, and I felt her push back just a little. That was all the permission I needed.
I slipped my hand between her thighs from behind, right there in the aisle, and rubbed her pussy through the dress. She was already wet, the cotton damp under my fingers. Lena bit her lip and stared straight ahead like nothing was happening while I stroked her slit, pressing the fabric into her folds. Passengers stood inches away, but the dim lights and the noise of the engine covered the wet sounds my fingers made.
"Fuck, you're soaked," I whispered against her ear. She shivered but stayed quiet. I worked two fingers under the hem of her dress and shoved them straight into her cunt. Lena's knees buckled. I held her up with my other arm around her waist, pumping my fingers deep and fast, thumb grinding her clit. Her juices ran down my hand. She clenched around me, trying not to moan as the bus stopped and more people squeezed on.
By the time we reached the back of the bus, near the emergency door, the crowd had thinned just enough. I pushed her against the rear window, yanked her dress up over her hips, and freed my cock. It slapped against her bare ass, thick and leaking. Lena spread her legs without a word. I lined up and drove into her in one hard thrust, burying every inch in her tight pussy right there on the moving bus.
She gasped, forehead pressed to the glass. I fucked her with short, brutal strokes, my hips slapping her ass while strangers stood only a few feet away. My balls swung against her, wet from her cream. Every bump in the road shoved me deeper. Lena reached back and grabbed my thigh, pulling me harder into her.
"Harder," she hissed. "Don't stop."
I grabbed her hips and pounded her, the wet smack of skin on skin barely hidden by the engine. Her cunt squeezed me like a fist. I reached around and pinched her clit, rolling it between my fingers until she came, her whole body shaking, pussy flooding around my cock. I didn't slow down. I kept slamming into her, chasing my own release, until I buried myself to the root and unloaded, pumping thick ropes of cum deep inside my sister while the bus rattled on.
We stayed locked together until the next stop. When I pulled out, my cum ran down her thighs. Lena smoothed her dress down like nothing had happened, but her flushed face and shaky legs told the real story. We rode the rest of the way in silence, my hand resting possessively on her ass, both of us already planning the next ride home.
