One who is regarded as a traitor. "Cheese" alludes to rats eating cheese, playing on the definition of "rat" meaning "traitor." The gang was determined to find the cheese-eater who told the police about their illegal activities.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
n. an informer; a rat fink. (Rats eat cheese.) Some cheese-eater called the clerk and warned her we were coming.
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.