get off one's tail

Also, get off one's butt. Stop loafing and start doing something. For example, Get off your tail and help your mother, or I should get off my butt, but I'm exhausted. Neither slangy expression, with its allusion to the buttocks, is considered polite.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.