blow the whistle

Expression

Expression
blow the whistle

(idiom) If you blow the whistle on someone, you report them to the authorities about illegal or immoral things that they may have done.
He blew the whistle on the corruption in the company.

They were fired from their jobs after blowing the whistle on the poor management of money in the company.
(sports) If you blow the whistle, this means a game or match ends or that a referee is going to do something.
The referee blew the whistle in the middle of the game after one of the players was fouled.