blow the whistle
 blow the whistle — see whistle, 1
 • • •
 Main Entry: blow
————————
 blow the whistle
  : to tell police, reporters, etc., about something (such as a crime) that has been kept secret
   — usually + on
   He blew the whistle on the company's illegal hiring practices.
   see also whistle-blower
 • • •
 Main Entry: whistle