bust (one's) nuts
rude slang To work very hard. "Nuts" is a slang term for testicles. I've been busting my nuts studying for this exam, so I really hope I get a good grade.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.