blow someone's cover
blow (one's) cover
To expose one's true identity or motives after they had been intentionally concealed (i.e. after one had been "undercover"). The spy fled when he realized that someone had blown his cover. I totally blew my cover when I stupidly wore my school jacket to steal the other team's mascot.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
blow someone's coverINFORMAL
If you blow someone's cover you tell other people who they are or what they are doing, when they are trying to keep it secret. Asking those kind of questions could blow my cover. The young man looked embarrassed, as if he were a spy whose cover had been blown.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012
blow someone's coverdiscover or expose someone's real identity.
Farlex Partner Idioms Dictionary © Farlex 2017
blow someone’s cover
tv. to reveal someone’s true identity; to ruin someone’s scheme for concealment. The dog recognized me and blew my cover.
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.