One evening a couple of years ago I was sitting around like any other night. My sister had a couple of friends over who were very developed for the age of 14. As they left my sisters bedroom I decided to take my laptop into my room and masturbate.
My bedroom is about 12 feet away from my sisters and the doors are right across the basement from each other. Usually I shut my door but this time for whatever reason I left it slightly open. I knelt near the door way next to the bed my computer was sitting on. I had been masturbating for about 3 or 4 minutes when it happened.
My sisters friend had silently come down the stairs. She was about 5'8" real tan with dark brown hair, long slim legs and a perky ass with nice perky tits. I glanced out the door and noticed her watching me stroke my 7 inch cock. This girl was probably familiar with masturbation and stuff, but I think this was the first time she had seen a real throbbing cock.
I lost all control and just kept stroking as she watched me. My sister and her other friend were waiting upstairs so within one minute she grabbed what she needed and went upstairs like nothing happened.
To this day we give each other looks but nothing has happened yet.