This happened three years ago.
My girlfriend and her friend got home from a night out. My girlfriend and I went to bed in the living room and her friend slept in the spare bedroom right next to the room we were in. I was really horny and could not sleep. My girl and her friend were asleep. I started wacking off and eventually was completely naked with no blanket on. I wanted her friend to walk in (the bathroom was in the room I was in) and see what I was doing. I stalled from cumming but nothing happened. She never appeared and I started to get soft.
I decided to see if I could peak into her room and see her legs and stuff. I crept over completely naked. I then heard some rustling, there was a blanket over the doorway so I really could not see inside the room. I then heard footsteps and before I could think my girlfriend's friend appeared at the door. She saw me and without even thinking and said 'J!' with a nervous chuckle and walked to the bathroom. I think she thought she had just caught me going to the fridge naked or something.
I looked down at my cock, I had no problem being hard now. I am eight inches hard but I swear I was at least nine at this time! I decided to stay and wait for her to get out. She came out and she was kind of surprised I was still there. I said 'will you please watch me' as I took my dick into my hand and began to stroke. She said she was tired and continued into the room. I explained it would only take a second and got onto the bed on my knees and began to jack. My leg touched her leg at one point. She said 'Tina is right next to us, she will think I am fucking you or something.'
I laid next to her and said 'just watch me cum.'
She told me to hurry, she was a little bit annoyed but watching my cock. I came everywhere, it was great cumming in front of my girlfriend's friend. I have a few more stories I will post later....