There is a difference between nudity and sex.
Although it's not common among American men, I think that men should feel comfortable being nude around one another regardless of sexual orientation. If we were more often I think it would solve most of the body image problems we face in this nation and most of the issues with prejudice as well.
We also wouldn't have these types of questions. Naked men around naked men are just... naked men. Brotherhood, bonding, camaraderie, and friendship at not 'gay'. If straight men were given the opportunity to not have to worry about that label we'd all be much better off.