Last night it was cold, and me and my Sis sleep in the same bed. Because of the cold, she moved closer to my side and spooned against me. I became rock hard as she kept wiggling to get closer warmer. My erection was sticking out of the button hole of my shorts and up against and in between her buns. I was wide awake and dared not move that she would feel my erection. She kept moving and I slipped in deeper between her thighs. Thankfully she was wearing p****** or I would likely have entered her. She was warm and soft, and her wiggles up against me felt wonderful down there. I was ready to c**, and resolved to just go ahead and shoot it all over her legs and p******… finally she was warmed up and moved back to her side of the bed…. oh my god, I was ready….. glad she moved, no idea how I would have explained the mess all over her.