Other than the usual group gym class/locker room showers, one pretty memorable experience:
During college, I was on spring break with a group of about 8 guy friends. All of us completely straight, as far as I know (that would include me, who at the time was not at all openly in touch with my bi side...). Anyway, one night after hitting a few bars, we decided to go to this place in town and get mineral baths (the town was in the mountains and known for its 'restorative waters').
Well, turns out this place was clearly geared for couples, which had we known upfront, we probably would have backed out. So, the proprietor asks us to pair up, ostensibly because we'd have to go 'through' the treatment in sequence of twos, given the small nature of the establishment.
Well, OK, we thought. So we did, not giving it much thought. I ended up paired with this guy, who I'll call Simon, who I liked but didn't know all that well. He was also pretty attractive -- though as mentioned, I was pretty deeply repressed about my bi side back then.
So, Steve and I start going through this whole elaborate quasi-medical 'process,' which began, of course, with us both having to strip naked. Things then progressed through being massaged, closely side-by-side, face up, on a single twin-bed sized massage-type table, with variuos oils, clay-like concoctions, etc.
After awhile, they then ushered us into this very small, dimly lit room,, with a single small pool of bubbling hot water. There was just enough room in the pool for two people to lay side by side -- which we did.
This was the weirdest part, because you were supposed to stay in the 'special waters' for a pretty long time. So here we were, to ostensibly straight guys, lying shoulder to shoulder, buck naked, in this very shallow but sensual bubbling pool (which was very clear, though, so everything of each other was completely visible and up close).
So Simon and I lay there in this warm bubbling water in this small room, all alone, for what seemed like about an hour. All the while, soothing quasi-romantic mood music being piped in.
We made a couple bemused jokes, but basically both sort of decided to lay back and enjoy it. Had we been a 'couple,' the ambience and setup of the place was such, that more than soaking was quite apparently very much expected and common among the guests.
Well, Simon and I didn't do anything (sigh!), nor, as far as I know, did any of the other guys in our group who'd been similarly paired off.
Afterward, there was a little tension-cutting joking amongst us, but not a whole lot of conversation. It had pretty clearly been a boundary pushing experience for all of us, I think.
It's the sort of thing that I wish in retrospect I'd been able to make more of. Still, a very nice and interesting memory.