(click ads, via) Very hard choice.
Left: a real scene that happened aboard a WWI army transport, gay-fully recreated. The hosing is particularly fun. Right: You got the guy behind the guy's behind; you got the guys staring at the other guys' behinds. And what's with the guy in the left stall with his hands behind his behind? Modest? Or receiving oral?
Previous homoerotically-charged vintage ads: Schlitz • Scandals skivvies.