blow the whistle vs play Judas

blow the whistle

verb
  • To make a piercing sound which signals a referee's action or the end of a game. 

  • 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. 

play Judas

How often have the words blow the whistle and play Judas occurred in a corpus of books? (source: Google Ngram Viewer )