work (one's) backside off(redirected from work their backside off)
work (one's) backside off
To work really hard (on or at something). I know you thought it was just a silly New Year's resolution, but I've been working my backside off at the gym! Sally and Jim work their backsides off when we hold our consumer conference each year. I don't know what I'd do without them!
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.