After a long day at work, I came home to an unusual sight. My step sister, who I hadn't seen in years, was getting fucked by some guy in my living room. I was shocked and aroused at the same time. The guy was pounding her hard, and she was moaning in pleasure. I couldn't help but watch as they went at it, their bodies moving in sync. The guy was huge, much bigger than me, and he was stretching her out in a way that I had never seen before. I could see her tits bouncing with every thrust, and it was driving me wild. I wanted to join in, to feel her tight pussy around my cock. But I knew that I had to be careful, that I couldn't let my desires get the best of me. I watched as they finished, him cumming all over her stomach, and I knew that I had to do something about it.