Once upon a time or so I've been told, a SGT was sent to Marble Mountain w/ a req for some extra beer from the flyboys. While he was waiting for it to be loaded, he helped himself to the the tap left unguarded (only the flyboys would be this trusting) behind the bar.
After enjoying several pulls, he went to the head to give back some of the borrowed beer. When he entered there were 2 bluebellies already at the trough. Since he was a large capacity Marine, he didn't finish until they were at the sinks. As he strolled past them, he overheard one of them say,"will you look at that, he didn't wash up!". Hearing this the SGT turned and said," in the Marine Corps they teach us not to piss on our hands." 'nuff said!