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Phrase(s): bust (one’s) ass (to do something) [and] break one’s balls to do something; bust one’s butt to do something; bust one’s nuts to do something
Sl. to work very hard to do something. (The expressions with balls and nuts are said typically, but not necessarily, of a male. Potentially offensive. Use only with discretion.) • I’ve been busting my nuts to get this thing done on time, and now they don’t want it! • The new boss expects you to bust your nuts every minute you are at work at the warehouse.
McGrawhill's American Idioms And Phrasal Verbs