I love getting naked in front of my friends and find it to be a bit of a turn. When I was a closeted teenager, I couldn't do it because I would get instantly hard, but gradually learned to keep it to a semi or lower, as it became normal (e.g. in front of college roommates). Now, when I share a room with a male friend for the first time, I'll find a time where I can show my junk, for instance, by dropping my drawers in my suitcase in front of him, then walking naked to the bathroom. Some friends will return the favor. Others don't, but I still like to show that I'm comfortable showing my stuff, although don't linger naked so long to make it uncomfortable for them.