work your arse off
work (one's) arse off
rude slang To work really hard (on or at something). Primarily heard in UK. I know you thought it was just a silly New Year's resolution, but I've been working my arse off at the gym! Sally and Jim work their arses off when we hold our user conference—I don't know what I'd do without them!
work your arse offBRITISH, VERY RUDE or
work your ass offAMERICAN, RUDE
If you work your arse off, you work very hard. He's working his arse off to make the shop his triumph. I'm working my ass off to get to where I need to be.