I would love to hear from guys with similar experiences.
I have a brother who is three years older than I am. We went to different high schools - he went to a public school and I went to a day prep school. We seldom saw each other after school until dinner time.
My younger sister took horse back riding lessons once a week, and my mother brought her to the lessons and stayed there until she was done, so one day each week I had the house to myself for a couple of hours. Being a typical horny fourteen year old, I never needed much of an excuse to jack off.
I had come home from school one day and undressed out of my school clothes (dress pants, coat, and tie), stripping down to just my boxer shorts and socks. This was one of those horse back riding days so, knowing that I would be alone for a while I flopped down on my bed, pulled my penis out through the fly of my boxer shorts, and began stroking it. It hardened up very quickly, and I began pumping away slowly, getting lost in my thoughts.
Now, I don't know if they snuck up on me, or if I was just so "involved" that I didn't hear them come in, but all of a sudden my older brother and his friend were standing in the doorway of my room, watching me stroke away. I immediately stuffed my penis back into my boxers, but it was too late - they had seen what I was doing. Besides, there was a noticeable tent in my boxers.
My brother and his friend weren't about to let me get away that easily. They walked over to me, one on each side of my bed, and without saying anything, they grabbed the legs of my boxer shorts and yanked them down, pulling them completely off. There I lay, naked, with my penis sticking straight up in the air with the two of them looking at me, my brother's friend holding my blue striped boxers in his hand. They made some rude comments about my erection and my pubic hair. I wanted to die. I begged them to give me my boxers back and to leave me alone. "No way", they said, "finish what you started." I protested, but totally in vain. I was trapped - they had my clothes, they blocked the door to the room, I couldn't get off of my bed. I had to do what they said.
Completely mortified, I wrapped my right hand around the shaft of my penis again, and slowly began to stroke it. And they stood there, arms folded, watching and snickering. I must have turned a thousand shades of red. But soon a funny thing happened - as I continued stroking I began to get more and more excited. It was a feeling I had not experienced before. Although I was at first terrified of ejaculating in front of them I began to think that it would be cool, that I was getting to show off my manhood to them. They were seeing me naked, seeing my pubes and my erection - it would be awesome to shoot off for them. I got more and more excited and pumped faster and harder. I probably had not been jacking off for too long, maybe about five minutes, but I was reaching the point of no return. I could feel the orgasm beginning and I didn't hold back. I kept pumping and exploded into a fountain of sticky white sperm. It shot up into the air and landed all over my stomach and chest. This seemed like the biggest orgasm I had ever had, and it certainly was the most that I had ejaculated up to this point.
My brother and his friend erupted into hysterical laughter as they watched me shoot my load. I kept pumping until there was nothing left. Then I stopped, and just lay back on the bed exhausted. Still laughing at me, they threw my boxer shorts back to me and left the room.
I don't know if they jacked off together after that. I imagine that they did - I know I sure would have. After that experience I wanted to show off to other guys, and I wanted my brother and his friend to see me shoot again. Unfortunately, that never happened. But that one time was a great experience.