I used to go to a small men only gym in San Francisco many years ago. They let me work out in minimal gear later in the evening, when there weren't many guys working out. I would wear my most scandalous gear, even doing squats in my jockstrap only. One night I wore my singlet that was super low cut on the sides and only had one narrow strap for the upper portion in the front. This meant that my cock was visible from the side. There was a super hot muscle guy there one evening working out and I got on the treadmill in front of him. He was very interested and turned on. This made me horny and I got a hardon. The motion on the treadmill made the singlet strap rub against my hard cock. The other guy got a hardon and started staring at my cock while he was doing his exercises. Pretty soon, I could feel myself getting close to shooting cause the strap was rubbing up against the sensitive underside of my cock. The other guy got closer to me and knew what was about to happen. Sure enough, my cock started squirting a huge load of cum that saturated my singlet and dripped out onto the treadmill. The guy watched the whole time it was happening and got a smile on his face.