A friend of mine is big into exercising, and one day he talked me into going to the health club that he was a member of. He could get me in as a guest so it was free, so I figured why not.
We worked out for a little bit and after a while he wanted to go sit in the steam room to relax. We were in there for probably a half hour when I had to go to the bathroom. I tried to hold off but it was getting urgent fast. I told him and went off to the bathroom, and it wasn't until I was standing in front of the urinal that it dawned on me that I only had a towel on, and I wasn't sure how it was going to work without exposing myself. Someone had just gone into the stall before I walked in, so that was out. I stood there for a few seconds before I decided I had to just lose the towel and go. I made sure no one was behind me and pulled it off, and I stood there completely naked in a public bathroom.
I started to go and just from the situation, I went from zero to horny in no time. When I was done I just stood there with my penis getting harder and harder. I was so horny I was shaking. The guy in the stall didn't seem like he was coming out soon, so I went for it. With the towel over my shoulder, I started masturbating right there at the urinal. My orgasm came almost immediately, shooting thick lines of cum all over the urinal. I admired the mess I made briefly before I went over and washed my hands, then tied my towel back on after my erection softened. Walking back, I could feel the wet spot on the towel from where the rest leaked out.
When I got back to the steam room my friend asked me what took so long, and I lied and told him I got lost. I think he bought it because he didn't say anything else about it. For the rest of the time we sat there I did feel more relaxed, but I know it wasn't just from the steam.