make (one’s) bones
v.— «They have reinstituted the requirement that before someone is made a soldier, he will have to ‘make his bones.’ That is, he will have to kill someone.» —“FBI Agent Nearly Was Inducted Into Mafia” by Larry Margasak AP Apr. 22, 1988. (source: Double-Tongued Dictionary)
Further reading
What if, instead of being an inanimate object, a dictionary were alive? That’s the idea behind a lavishly illustrated new children’s book called The Dictionary Story (Bookshop|Amazon) by Oliver Jeffers and Sam Winston. This is part of a...
Cat hair may be something you brush off, but cat hair is also a slang term that means “money.” In the same way, cat beer isn’t alcoholic — some people use cat beer as a joking term for “milk.” And imagine walking on a...