I normally go to the gym at least once per week. I am not big or anything, but I like to swim there to try to stay in shape. Most of the people that go there are around my age, but every now and then there are some older people there too.
Normally, I never have any problems when I go there, but that changed one day a couple weeks ago. After I finished swimming, I went to my locker to grab my dry towel and went to the showers to rinse off the chlorine. I dropped my towel on the bench outside the stalls, walked in, pulled off my swimming trunks, tossed them out to that same bench and closed the curtain. Since the water was running, I couldn't really hear anything going on outside. When I was finished, I reached out to grab my towel, but it wasn't there. I looked outside and my trunks were gone too. I guess some little asshole thought it would be funny to take my stuff.
I stood there panicking for a couple minutes, but I realized that I couldn't just stay in there forever. I poked my head out to see if anyone was there, and since there wasn't, I got out and made my way down to the locker room wearing nothing but my shower sandals. When I got to the lockers, I could tell that there were a couple guys on the other side of the room, but they were talking about lifting weights, so I figured they wouldn't even know I was there. I hurried over to my locker and grabbed my jogging pants and got back to the hallway as fast as I could. By this time, I guess because of the risk of getting caught, I was completely hard, so my 6 inch penis was bobbing back and forth with every step I took.
It didn't take long to get back to the showers, and when I got there I jumped in one and closed the curtain behind me. My heart was going a mile per minute, but even after standing there for a few minutes, my erection would not go down. I guess out of habit, my hand made its way down and took hold of my throbbing penis and started stroking. Again, I guess from the risk of getting caught, I was very, very horny. At this point, I didn't even care if anyone was around, because I needed to cum. Leaking precum like a faucet, my stroking started making squishing sounds.
I was starting to get close, when I heard someone walking down to the showers. My head knew I should stop and stay quiet, but my hand kept on going. He started to walk by, but I guess when he heard me, he stopped and took a step back. I could tell by looking at his bare feet that he was about my age or maybe a little younger, and my heart nearly stopped when he asked me 'dude, are you jacking off in there?' I couldn't help it, but I started stroking faster, and a few seconds later I croaked out a 'yeah'. He then said 'cool, I was gonna do the same thing' and walked away. Hearing him say that sent me over the edge and cum started pouring out the end of my penis, shooting out at least 5 strong ropes before dribbling out over my hand.
I stood there for a couple minutes catching my breath and then turned on the water to wash all of it down the drain, put on my pants and walked out. I walked down the line, and saw him in one of the stalls completely naked with the curtain half open. His back was to me, but I could see him stroking himself hard. I asked him 'aren't you worried someone will see you?' He said to me 'let them look, I don't care, I'm not going to hide it'. I asked if he was having fun with it, and he said 'oh man, I am about to cum so hard.' I stood there for a few more seconds until he let out a loud moan and leaned against the wall as his cum started hitting the floor. Seeing all of it, I said to him 'damn, I bet that one felt really good', and he said back 'oh yeah, I haven't cum in three days'. With all of this, I started getting hard again, so I went back into a stall, kicked off my pants and sandals and started masturbating again. Since I was in the stall right next to him, he could hear me so he asked 'are you doing it again?' I said I was and told him to come on over. I heard him come out and he walked into my stall with a half-mast that started growing again and topped out at almost 8 inches and thick. Fully hard, he started matching me stroke for stroke. No one has ever watched me masturbate before, so with that other pair of eyes on me, it didn't take long until I was cumming again. It wasn't as much as the first time, running out all over my hand. He took a little longer, but when he was about to blow, he leaned back, grunted and shot another huge load all over the floor. We both stood there for a few minutes reeling in what happened when, again, I could feel my penis growing for the third time. I squatted down and started playing with it, and he asked me 'damn man, again?' I looked up and said 'may as well, we're already here.' He sat down across from me and said 'ok, if you insist' as he started squeezing and stroking himself, getting it hard again. This time took a bit longer, being the third session, and when I came, it wasn't much more than a drop squeezing out. After that, my penis actually hurt, so I knew I was done. He was still going, so I just sat back and watched him. Eventually, he was about to cum again, and he started saying things like 'oh, I'm gonna cum, I'm gonna cum'. His toes clenched and he blew a smaller load than before, but still enough to cover his hard-on. He leaned his head against the wall and said 'ohhh shit...' and let his big, wet cock flop against his belly.
After we got ourselves cleaned up, we went back to the lockers and talked for a while, mainly about that. It turns out, he jacks off in the showers at least once a week, and he said that I should join him again sometime, which I said I might.
I never found out who took my stuff, but I did, however, have some real fun masturbating again and again thinking about what happened.