bust (one's) butt(redirected from busting their butts)
bust (one's) butt
1. (acting upon oneself) To exert a significant amount of energy or work very hard to do, accomplish, or complete something. I've been busting my butt all night long to get this presentation ready for tomorrow's meeting. She's going to have to bust her butt if she wants a place on the varsity team.
2. (acting upon someone else) To harass, nag, or upbraid someone to do, accomplish, or complete something. The boss is busting everyone's butt to get the project ready by next week. Quit busting my butt! I'll get it done eventually!