After discovering masturbation at almost 13 I could not stop doing it at every possible moment. I didn't even pay much attention weather I was home alone or not. The first thing I did after coming home from school was changing into my jacking pants, which were some comfortable jogging pants with plenty of space for expansion. After lunch I would go up into my room and starting homework. It usually didn't take long before my penis was getting hard. When I wasn't home alone, I usually started humping my pillows with my pants on, only taking them down for ejaculation. Before I figured out the tissue thing, I would ejaculate into an old preserving jar and watch the semen float around. For a while I was collecting the semen, trying to fill up the jar. Needless to say, the jar started stinking pretty bad after a few days and I had to toss its ingredients in the sink and have the dishwasher clean it out.
At that time it wasn't rare that I jacked off 3 or 4 times in one afternoon, mostly with the same technique, humping the pillow and squirting into the jar. Usually the first orgasm of the day produced 3-4 drops of semen while the last ones hardly produced any liquids.
When I was home alone I loved running around the house naked with my boner standing straight up. Whatever I was doing, I made sure my penis would not go soft. I could sometimes enjoy that for hours before I gave in to a powerful orgasm.
On the weekends I also had the opportunity to jack off in the shower. One time I enjoyed an especially long hot shower until I made myself cum. The powerful orgasm and the hot steamy air in the bathroom almost caused me to fade. I was getting black around me and I could feel sinking into my knees. It took all my strength not to loose consciousness. After that incident I tried to minimize my shower sessions.
One particular rememberable session happened when I was home alone. I was naked in the house as often. I walked into my parent's bedroom and kneeled in front of the large mirror, spreading my legs apart as far as I could. I investigated my body in the mirror. My penis was maybe 4 inches long at that time I had no black pubic hair yet, only some blonde ones on my scrotum, which I could only see when I looked really close. I was fascinated watching my marble sized testicles, which moved around depending on the degree of stimulation. When I left my penis alone for a while my scrotum would get longer and saggier. When I started touching my penis again, my testicles would pull up closer to my penis and get tenser.
This one day I watched myself for a while in the mirror and played with my penis. All of a sudden I could feel that I had accidentally crossed the line of no return. I kept my hands away trying to stop the oncoming orgasm. But my penis grew another half inch or so and inched even higher standing almost vertically up. My testicles tensed up like before a regular orgasm but they didn't start pumping for quite a few seconds. It was an incredible feeling and I almost couldn't take it but on the same time I enjoyed it immensely.
After a few seconds I felt the first weak twitch, then another one and then the twitching got stronger and faster. At one point it felt like my testicles had opened the floodgates and semen could just run out in one long stream until the orgasm slowly subsided with my penis still twitching and jumping up in irregular intervals. It was one of the best orgasms I had ever had. And it had pretty much exhausted me. Once I came back to senses I noticed quite some amount of semen on the carpet in front of me. It wasn't that much by today's standards but for that time it was huge. Of course I had to clean up this mess, which I did with a wet towel. After that I went back to my room for a rest on my bed. I didn't have the energy to dress before I heard my parents coming home