"It takes a lot of brass to play all those trombones in a dorm at 3:00 AM." Double entendre, no euphemism.
Isn't brass a euphemism for something else, such as "It takes a lot of balls..." But you replace it with 'brass' as to not offend, which is what euphemisms are.
isn't being used in a literal sense so
brass isn't really being used as a euphemism for
balls. Even in something like, "It takes a lot of nerve ..."
nerve isn't being used in a literal sense. These are all being used metaphorically. If they had been talking about any of a number of sports games, using
balls could be considered double entendre. The fact that they were talking about a brass instrument makes the use of
brass the double entendre but it's not really a euphemism.
