Of course there is

"Is there anything else you'd like for your birthday present, Phil?" My oldest sister Stacy asked in her strange sleepwalking trance as she knelt there naked by my bed.

I took a deep breath, my mind racing with the possibilities of this situation, of what could happen... even as part of me struggled with what should happen. I knew I should stop this, I should send Stacy away, pretend that this never happened, but I couldn't. I was too aroused, too excited to let this opportunity slip past me. "Yes, Stacy, there is," I assured my sleeping sister as I sat up on my bed, my cock hardening instantly. I wondered briefly at my quick recovery, normally it'd take me at least a few minutes to get fully hard again after such a powerful climax but now, simply the thought of continuing with my somnambulist sister had my cock pulsing in eagerness.

"What is it, Phil?" Stacy asked in her drowsy tone of voice, her face blank of all expression as she sat there by my bedside. "What else do you want for your birthday present?" She asked, spreading her legs slightly, exposing the swollen lips of her pussy to me as if anticipating my answer.

"I want you," I answered her with an eager smile, relishing this moment even as I wondered at the strange circumstances that had led us here. "I want to fuck you, Stacy," I assured my sleepwaking sister, my lust pushing any moral objections aside as my eyes ran over her slender shapely body. "I want your pussy for my birthday present."

"It's all yours, Phil," Stacy replied with a dreamy smile on her face as she stood up, letting me get a good long look at her naked body before she climbed onto the bed with me, her hand pressing against my chest, pushing me back onto the mattress as she straddled my waist. "I've wondered what this would be like for a long time now, Phil," my sleeping sister confides in me as her hand reaches down, stroking my hard cock as she positions herself over me. Her long slender fingers slide up and down my shaft as she presses the swollen head of my cock against the wet warm lips of her pussy, holding herself there for a brief teasing moment before lowering herself down, impaling herself on my hard cock in one full motion.

"Fuck," I hissed, my hips lifting up off the bed, my hands reaching up to grip her slender hips as my sister starts gently rocking her hips against me, slowly fucking herself on my engorged cock. "That's sooo good," I moaned, my hips moving in time with hers, prolonging the moments of contact as she rides me. "So fucking good."

"I'm glad you like it, Phil," Stacy replies with a contented grin, her body beginning to move faster, rocking harder and harder against me as the pleasure builds between us. "We can do this anytime you want. I am yours whenever you want me," Stacy assured me between gasped breaths, her body moving in a pulsing, feverish pace as she fucks herself on my cock.

"Anytime?" I ask with a grunt, the idea of fucking my oldest sister sending a thrill of forbidden pleasure through me, my body tensing as I felt the second powerful orgasm of the night beginning to build within me. Even then, I somehow knew that she meant only when she was in this state, only when she was "sleepwalking" would she willingly be mine... but that was enough for me.

"ANYTIME!" Stacy cries out, her body bouncing up and down on me with abandon as her own orgasm surely built within her, her body tensing as the climax washed through her, her pussy convulsing in spasms of delight around my hard cock, milking my climax out of me.

"Fuck," I moaned as I came, thrusting my hips up hard, holding myself deep inside her as my cock bucked and jerked, shooting my seed deep into her. I didn't think about the consequences, of what could happen from having unprotected sex then, I only began to worry about later, much later, when it was already too late. "That... that was good... Stacy," I managed to pant as I lay there, recovering from my second powerful orgasm in a short period of time.

"I'm glad you liked it, Phil," my older sister replied with a smile as she climbed off of me, my still hard cock slipping out of her flooded sex with a wet popping sound. "We thought you'd enjoy your birthday present," she assures me enigmatically in her strange sleepwalking state as she stands up.

"We?" I echoed in confusion, sitting up and regarding her carefully. "Who is we?"

"Why don't you come downstairs and find out?" Stacy replies with a sphinx-like smile as she turns and ambles out of the door, her body moving with that easy aimless shuffle of a sleepwalker.