This happen many yeara ago.
I was in a small town in West Virginia on military business. I saw a local pool and being a hot day, thought I'd check it out. I didn't have any swimwear so inquired if I could rent. The highschool girl at the desk got me a pair of white speedos, took my money and I went into the changing room.
In there was a mother about 30 years old with her young son getting him changed. I noticed another man naked walking around and she ignored him. I kind of shrugged and stripped down. She tried to ignore me but made sure she got a good view.
I went into the pool area and it was mostly high school kids and younger because it was a weekday. I swam a bit and looked for a place to relax. I was a vacant lounge and decided to use it. It was a short distance for 3 girls all in their teens. I lay down and was relaxing when I heard the giggling. I then noticed my speedos were practically sheer and my entire package was on display. This made be begin to bone up and my package became more pronounced. After a whild of ignoring them, I noticed other girls talking to them but I also noticed the speedos had dried and were no longer see-through.
I again went into the water and swam for a few minutes and went back to the lounge. This time, I made sure the speedo's wer about 1 inch lower so my cock would be even more visible. I pretended I didn't know they were looking at me so I would scratch my package a bit now and then. I was getting visibly aroused so my package was quite pronounced. They got quite a show with me even holding the material away from my leg occasionally.
Finally, I had to leave. The entrance to the changing room was a chance to really expose myself. I entered and removed the suit and made sure I passed the entrance having left the door open.
this was not wasted energy because the 2 girls were chatting with the female lifeguard and could see me totally naked.
When I left, the girl at the desk to whom I returned the suit said, Come again--it was good to see all of you.