I lay back on my couch, my heart racing with anticipation. Step-Mom had bought me a special gift - a thick, veiny dildo shaped just like Step-Dad's cock. She said it was time I learned how to please myself properly. My hands trembled slightly as I tore open the package, revealing the impressive silicone shaft. I couldn't wait to feel it stretching me open. Spreading my legs wide, I brought the tip to my already dripping entrance. Slowly, I began to sink down onto it, biting my lip to stifle a moan. It felt so big, so much bigger than my small fingers. Inch by inch, I took more of it inside until I was fully seated. "Oh fuck," I continued, slowly starting to bounce on the thick toy, riding it with increasing enthusiasm. The sensations were incredible, far surpassing anything I'd experienced before. Each downward thrust made me gasp and shudder, pleasure building rapidly in my core. Lost in bliss, I barely noticed when the door creaked open. Suddenly, I heard a sharp intake of breath behind me. Freezing mid-bounce, I glanced over my shoulder to see Step-Dad standing there, eyes wide with shock...and undisguised lust as he took in the lewd sight of his step-daughter impaled on a huge dildo, tits bouncing with each movement. "step-Daddy!" I yelped, instinctively clenching around the toy inside me at being caught. But instead of scolding me, he swallowed hard, Adam's apple bobbing. "That's it girl, ride that cock," He stepped closer, voice low and husky with desire. "Fuck, you look so hot like this. Such a naughty little thing, playing with toys meant for grown-ups." Emboldened by his reaction, I started moving again, putting on a show. I arched my back, presenting my ass to him as I bounced faster. The wet squelches of the dildo pumping in and out filled the room. "That's right Step-Daddy, watch me. Watch your dirty girl fuck herself silly." I reached back to spread my cheeks, giving him an even better view. "Don't you wish this was your real cock stretching me open?" He groaned, palming himself through his pants. "God yes, I want to bend you over and pound this tight little pussy raw. Want to fill you up with my cum until it's leaking out of you." His filthy words pushed me over the edge. Throwing my head back, I came with a loud cry, spasming intensely on the dildo. "FUCK Step-DADDY, I'M CUMMING!" Wave after wave of mind-blowing ecstasy crashed through me as I rode out my high. When I finally went limp, I looked back at him with glazed eyes and a satisfied smirk. "Mmm, that was amazing. Thank you for watching, Step-Daddy. I love putting on shows for you." He smiled wickedly, still rubbing his obvious erection. "Anytime, princess. Feel free to use your new toy anytime you need. And if you ever want the real thing..." He left the offer hanging as he turned and walked out, leaving me achingly aroused and craving more.