Not guys, but I had a female life guard come on to me once.
In college, the pool that I worked out at maintained men only and women only hours for the pool. The locker rooms were directly connected to the pool. When it was the women only hours the men's locker room door to the pool was locked, and the opposite when it was the men only hours. It was very common for the men that used the pool during those hours to swim nude. I really enjoyed doing my laps au natural, but then I grew up in a home that was very open to nudity. I was told by a friend that worked there that the women only hours were even more popular than the guys, and that nearly all the women went nude, compared to about half the men.
My friend said that scheduling of life guards for the pool was always a hassle. Ideally they tried to schedule male life guards for the men's hours and female life guards for the women's hours. But as the facility employed more female life guards than male this was not always possible. The facility would only schedule female life guards for women, but the men only hours had a mix of male and female life guards. Nice double standard, but the who said life was fair. Some guys objected, and others of us said we did not care. That may be a reason why only 50% of the men went nude at the pool.
Friday evenings the 2 hours before close was the evening that I would usually do my 5000 yard work out, It was also seemed to be a time that the pool could not get any guys to work as life guards. Most of the time there was a female life guard. I would start my laps and there would be a fair amount of guys in the facility. By the time I finished my workout I typically was the only one left in the pool. Following my laps I would return to the men's locker room and have a little extra time to shower and take a sauna.
One evening after my swim I was relaxing in the sauna when the female life guard that had been on duty in the pool came into the sauna. She stripped naked and climbed onto the bench I was laying on. She told me that for weeks she has been getting super horny as she watched me do my laps naked every Friday night, and at the end of the shift she would masturbate in the women's locker room fantasizing about my cock. That night she was done fantasizing and that she need to have my big cock.
That was the start of a very hot evening. She had locked up the pool and we were the only ones left in the building. We spent hours screwing everywhere in that building. She was a bit taken back when she found out how big I was. She said she had imagined that I was big, but never imagined that any guy's cock got as huge as my monster erection did. But she had chosen her path when she walked into that sauna and stripped, and she wanted it no matter how big it was.
For the next semester nearly every Friday night started with my long swim work out, and finished with a marathon session of sex with my favorite life guard.