<Channeling Homer Simpson> "... Mmmmmmmmmmmm......showers......."
Yeah..... Showers REALLY do it for me..... I never turn down an opportunity to shower with another guy.
That said, I've noticed a few things over the years:
Standard shower stalls really aren't big enough for 2 guys to do very much. One place I've taken classes has a single stall and a water heater that can't keep up. We usually shower two at a time. We're basically sandwiched together so we have to wash each other down. Obviously this makes for a lot of silly fun (e.g. "Oh, let me give this a few extra tugs to make sure it's clean") and nobody ever complains. However, there simply isn't enough room to do more than this:
https://www.lpsg.com/attachments/men-in-the-shower-9-jpg.987781/
Showers in a standard sized tub are a bit better, but if there's just one showerhead, one guy's left in the cold.
Another thing: Giving a guy a blowjob with the shower stream hitting you in the face is not as hot as it looks in porn. Cock-in-the-mouth + water == breathing difficulties.
You'll notice in porn that the showers in all those hot scenes are WAY bigger than a standard shower is.
These are serious issues, but have they ever stopped me from showering with another guy? HELL NO!