The bathroom door clicked shut behind us, the sound echoing off the tiles like a starting gun. I shoved my sister against the sink, my hands already yanking her shorts down her thick thighs. "You've been holding it all day, haven't you, you filthy slut?" I growled, voice low and rough. She grinned that wicked grin, the one she only gave me when Mom and Dad were gone.
"Since breakfast," she admitted, spreading her legs so I could see the damp spot on her panties. "My bladder's killing me. You gonna help me with it or just talk shit?"
I dropped to my knees and ripped the fabric aside. Her pussy was already swollen, lips puffy and glistening. I pressed my mouth right against her slit and ordered, "Piss. Right now. On my tongue."
She moaned and let go.
A hot, salty stream hit my mouth, strong and steady. I swallowed the first mouthful, then opened wider so it splashed across my face, running down my chin and soaking my shirt. The smell filled the small room, sharp and intimate. I lapped at her while she emptied herself, piss mixing with the slick juice already leaking from her cunt. When the stream slowed to a trickle I stood, spun her around, and bent her over the counter.
My cock was rock hard and leaking. I slammed into her in one thrust, burying myself balls-deep in her wet heat. She gasped, gripping the edge of the sink. "Fuck, yes—use me. Fill me up again."
I fucked her hard and fast, the wet slap of skin loud in the tiled room. Every time I bottomed out she pushed back, grinding her ass against me. I reached around and rubbed her clit in rough circles. "You want more piss? Tell me."
"Give it to me," she panted. "Piss in my cunt while you fuck me."
I slowed my strokes, focused, and let go. Hot urine flooded her pussy around my cock, mixing with her juices and my pre-cum. It overflowed, running down her thighs and dripping onto the floor. The sensation of pissing inside her while buried deep made my balls tighten. I kept thrusting through it, the liquid squelching obscenely with every stroke.
She came first, legs shaking, cunt clenching around me as she squirted a mix of piss and cum onto the linoleum. I didn't stop. I pulled out, aimed my still-hard dick at her ass, and let the last of my piss spray across her cheeks and hole. Then I shoved back in, this time into her tight ass, using the piss as lube.
"Goddamn, your ass feels even better when it's wet like this," I grunted, pounding into her. She reached back and spread her cheeks wider for me. I spat on her hole for good measure and kept going, balls slapping against her piss-soaked skin.
We moved to the shower when the floor got too slippery. I turned the water on cold at first, then hot, and we stood under the spray, me still buried in her ass. She turned around, dropped to her knees, and took my cock straight from her ass into her mouth, sucking greedily. "Taste yourself on me," I told her. She moaned around the shaft, eyes watering as she deep-throated me.
I pulled her up, lifted one of her legs, and fucked her standing, one hand gripping her throat, the other rubbing her clit again. "Piss on my cock while I fuck you," I demanded. She did, a fresh hot stream pouring over my shaft and balls while I thrust. The heat and pressure pushed me over the edge. I came deep inside her, groaning as I pumped load after load into her flooded cunt.
We stayed locked together under the water, breathing hard, piss and cum and sweat swirling down the drain. She kissed me, tongue pushing into my mouth so we could share the taste. "Same time tomorrow?" she whispered against my lips.
I slapped her ass, still dripping. "Count on it, sis. Next time I'm filling your mouth first."
We cleaned up just enough to not leave obvious evidence, then slipped back to our rooms before our parents got home. The whole house smelled faintly of sex and salt, but only we knew why.
