You're becoming quite the pervert these days. Being a virgin is too much to bare at time, so sometimes you jerk your virgin penis over your hot step sister as she blissfully sleeps, unaware of your dirty wanking. But she catches you, and although mad at first, she pities her step brother and allows him to carry on rubbing your cock as she strokes and fingers her wet pussy... but remember, this is a one time thing!
