"Hey big brother, truth or dare?" Lisa called from the dock, her voice carrying over the water with that familiar teasing lilt. We were alone at the family lake house for the weekend, parents off on their cruise, and the old game had started up again like it always did when we got bored.
"Dare," I shot back, grinning as I paddled the kayak closer. At twenty-four and twenty-two, we were way past the innocent version.
"I dare you to skinny dip right now.
No whining."
I laughed, already peeling off my shirt. "Only if you join me, sis. Fair's fair."
She stripped down fast, her body pale and perfect in the afternoon sun, and we hit the water together. Splashing turned into wrestling, her legs wrapping around my waist as she tried to dunk me. "You're hard already," she whispered, playful and breathless. "Pervert."
"Like you're not wet for more than the lake," I fired back, hands sliding down to grip her ass. She moaned into my ear and ground against me, our game shifting fast.
We climbed back onto the dock, dripping and laughing. "Your turn," she said, pushing me onto the towels. "Dare me to suck my brother's cock."
"Dare," I groaned, spreading my legs. Lisa dropped between them, her mouth hot and eager as she took me deep. "Fuck, sis, that's it. Suck it like you mean it."
She pulled off with a pop, eyes sparkling. "Mmm, tastes like trouble. Remember last summer when we almost got caught?"
"Yeah, and it made it hotter," I said, pulling her up to straddle me. She sank down slow, her pussy tight and slick around my cock. "Ride me, little sis. Show me how much fun we can have."
Lisa bounced with wild energy, tits bouncing as she moaned loud enough to echo across the lake. "God yes, fuck your sister harder! Fill me up, big brother!"
We switched positions, me pounding her from behind while she clutched the dock railing. "Spank me," she begged between laughs and gasps. "Tell me I'm a bad girl for wanting her brother's dick."
"You're the best kind of bad," I grunted, slapping her ass red. "This pussy's mine all weekend."
By sunset we were tangled on the cabin floor, trading filthy dares between rounds. "I dare you to come in my mouth," she said, sucking me clean after the third time. We kept going until dawn, every round dirtier and more playful than the last, the house filled with our laughter and moans.
By the time our parents texted they were heading home, we were already planning the next "game night."
