blow the whistle
- (idiomatic, usually with "on") To disclose information to the public or to appropriate authorities concerning the illegal or socially harmful actions of a person or group, especially a corporation or government agency.
- In some jurisdictions, it is illegal to fire a person for blowing the whistle on an employer.
- (team sports) To make a piercing sound which signals a referee's action or the end of a game.
disclose information to the public
make a sound which signals a referee's action or the end of a game