fair game vs gull

fair game

noun
  • Used other than figuratively or idiomatically: see fair, game.: a game that is fair, that does not involve cheating, etc. 

  • An acceptable subject or target for criticism, scrutiny, mockery, or attack. 

  • A goal or an object that may legitimately be sought. 

  • Actions permissible by the rules. 

gull

noun
  • A cheating trick; a fraud. 

  • A seabird of the genus Larus or of the family Laridae. 

  • Any of various pierid butterflies of the genus Cepora. 

  • One easily cheated; a dupe. 

verb
  • To trick and defraud. 

  • To deceive or cheat. 

  • To mislead. 

How often have the words fair game and gull occurred in a corpus of books? (source: Google Ngram Viewer )