child's play vs pleasure cruise

child's play

noun
  • Something particularly simple or easy. 

  • Used other than figuratively or idiomatically: the play of a child. 

pleasure cruise

noun
  • A pleasant or easy situation without any challenges. 

  • A pleasure trip, especially on a ship. 

How often have the words child's play and pleasure cruise occurred in a corpus of books? (source: Google Ngram Viewer )