get one's rear in gear get one's rear in gear {v. phr.}, {slang} To hurry up, to get going. I'm gonna have to get my rear in gear. Categories: add yours {slang} {v. phr.} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2024 To section: G Subscribe to: American IdiomsIdioms feedEnglish languageHome page and general feed Discuss