Yeah...whenever I've shared a bathroom with a roommate or a friend (e.g. at a hotel), I let them know it's ok to use the toilet or sink while I'm in there. Most have reciprocated the offer. Since it's just among guys, It makes no difference if the shower has an opaque shower curtain or clear glass. I've been using gyms with open showers since college, so I'm totally used to other men seeing me scrub my penis. I'm also at ease being the one taking a leak in sight of my friend.