The two of us wandered around the class looking for more dust to grope the other person with, We ended up in a storage room at the back of the class. ...Because the art teachers wanted stuff to dry in the storage room, the door was to remain closed unless your going in or out, Down in a corner was another pottery shelf. Thankfully I noticed it first and subtly wiped my hands over it. I walked back over to Katherine and got within half a foot of her. I looked her in the eyes and with one hand. We sat on the couch just beside each other.At the time I don’t have any feeling towards my sister. Suddenly, during the problems session, I had got a glimpse of my sister lovely boobs from under her neck. By seeing that I got much tensed and am not able to take my eyes away from that scene. She is doing her work and never noticed me.I some how want to catch them in my hands and press them, I pretended as if am explaining the solution and tried to press her boobs with my elbow. She had no. I pulled them down over his cock. I went back up to his cock it was fully erect. I was excited my self, I flikered my tounge around the head of his cock. He moaned and said yes babe. I said you like that he said yes yes, there was a little pre cum i of course cleaned it up. Dam his cock was big and smoothe no hair anywhere. He had a big cough in his living room so i laid him down on his belly. I took of all my clothes and sat between his legs, I was hard and wet too. I started to rub my cock up. But it had been different then, I'd been fucking my girlfriend in the next room. This time I was on my own.As the noise from the next room got louder, I started to turn the volume down on the TV. He was really fucking her hard and she was really enjoying it. I was getting really turned on listening. I had my own personal porn performance taking place less than six feet away and soon I was as hard as a rock imagining her. She was quite frank and filthy when it came to sex and Pete was less.