work one’s tail off

work (one's) tail 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 tail off at the gym! Sally and Jim work their tails off when we hold our consumer conference each year. I don't know what I'd do without them!
See also: off, tail, work
Farlex Dictionary of Idioms.

work one’s tail off

and work one’s ass off and work one’s buns off and work one’s butt off
tv. to work very hard. (Often objectionable.) You spend half your life working your butt off—and for what? I worked my buns off to get this done on time!
See also: off, tail, work
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • I've got work to do
  • go shares
  • off
  • offed
  • be at work
  • be your own master/mistress
  • mistress
  • be (one's) own master
  • hard work is not easy
  • off from work