I walk in to my bedroom and I find my step-mom lying down on my bed. She is wearing a purple bath robe and she has a cell phone in her hands. "What are you doing in my bedroom?!" I ask her. "I was just looking at some porn!" she giggles. She mentions the blowjob that she gave me earlier, and that she is still horny. "I bet you can get hard just from my ass!" she tells me. "If you do get hard, your prize is that you can fuck my ass!" she says. I can feel my cock starting to get hard already. I hop on to the bed and I slowly start to shove my hard cock inside of my step-mom's ass. I fuck her ass nice and slow at first, since I've never done this before! After a few minutes, she flips over on to her back so I can fuck her ass in the missionary position next. She starts to rub her clit, while I keep fucking her tight ass! When I get close to cumming, I jerk my cock off in to her mouth while she stares up at me. She swallows all of my cum!