flip out flip out {v. phr.}, {slang}, {informal} To go insane, to go out of one's mind. A is impossible to talk to Joe today — he must have flipped out. Categories: add yours {informal} {slang} {v. phr.} Source: A Dictionary of American Idioms by A. Makkai, M.T. Boatner, J.E. Gates © 2024 To section: F Subscribe to: American IdiomsIdioms feedEnglish languageHome page and general feed Discuss