I usually work out twice a day at a local gym near me. I had just finished a hard work out and the gym was about to close. I also work at this gym and my boss said I should lock up after I was done showering and leave.
As he said that, a guy came in and asked if he could get a quick thirty minute workout. I said it was fine with me if it was ok with the boss. My boss said it was cool and left.
After I finished my workout I went to sit in the sauna but didn't take an extra towel so I went in wearing just my thong. I was there about five minutes when the other man, who was about 25, came into the sauna. We chatted about sports and all kinds of other things.
He was wearing a towel and commented that he thought my thong was a nice touch. He asked if it was comfortbale and I told him that it was very comfortable. Then, he asked if I minded if he took off his towel, and I said no, I didn't. I'm bi, but I didn't want to tell him that.
We chatted some more and I started to become aroused. The other guy was also becoming aroused, and he asked if he could try on my thong. I said, sure, but for them to fit right, he shouldn't have an erection. He looked at my erection and said that it must be hurting mine, then, so I took off the thongs, and sat back down and we both jerked off into the hot sauna rocks that hissed as we shot our cum on them.
Afterwards he tried on my thongs and agreed they were quite comfortable.