I promise you I'll work my tail off for you.
Here it is, two o'clock in the morning, and she's been working her tail off.
He should do what other teachers do: work his tail off doing something too few people appreciate.
He works his tail off, and that's why he's so good.
Your husband, in case you hadn't noticed, is now going out all day just about every day working his tail off.
"If they give me nothing, I have to work my tail off," he said.
He has worked his tail off for 25 or 30 years.
Tired of working your tail off just to break even?
I'm working my tail off and not getting faster.
He works his tail off and shows the other guys how hard we have to work.