stool pigeon
stool pigeon. Slang. 1. An informant, esp. a police informant. 2. A person who acts as a decoy, esp. on behalf of a gambler or swindler, or for the police to help make an arrest. — Also termed (in sense 1) rat; (in sense 2) capper.
stool pigeon. Slang. 1. An informant, esp. a police informant. 2. A person who acts as a decoy, esp. on behalf of a gambler or swindler, or for the police to help make an arrest. — Also termed (in sense 1) rat; (in sense 2) capper.