I've showered with a few female friends, but that was a locker room/etc scenario, or else it was friends I have had sex with, who I've showered with. Otherwise, I haven't casually showered with friends. I have never casually/platonically showered with any male identifying friends. Other than locker room shit, I don't make a point of seeing friends nude, because most don't do it comfortably. I definitely do not make a point of ogling my friends, male, female, whatever.
I have never seen any male friends nude that I have not been intimate with/planned to be intimate with. If one whipped out his dick/overtly flashed me, the fucker better have a ring, barbell, or tattoo on that shit. Or some weird health thing, I guess, but then I would just tell them to go to their doctor. Otherwise, there is no reason for them to flash me.