knock on wood vs scout

knock on wood

verb
  • To take a customary action to ward off some misfortune that is believed to be attracted by a presumptuous statement. 

intj
  • Hopefully; a self-directive to undertake the customary action to ward off bad luck. 

scout

verb
  • To reject with contempt. 

  • To scoff. 

  • To pour forth a liquid forcibly, especially excrement. 

  • To explore a wide terrain, as if on a search. 

  • To observe, watch, or look for, as a scout; to follow for the purpose of observation, as a scout. 

noun
  • A fighter aircraft. 

  • Term of address for a man or boy. 

  • An act of scouting or reconnoitering. 

  • A member of any number of youth organizations belonging to the international scout movement, such as the Boy Scouts of America or Girl Scouts of the United States. 

  • A person employed to monitor rivals' activities in the petroleum industry. 

  • A fielder in a game for practice. 

  • A housekeeper or domestic cleaner, generally female, employed by one of the constituent colleges of Oxford University to clean rooms; generally equivalent to a modern bedder at Cambridge University. 

  • A preliminary image that allows the technician to make adjustments before the actual diagnostic images. 

  • The guillemot. 

  • A person who assesses and/or recruits others; especially, one who identifies promising talent on behalf of a sports team. 

  • A domestic servant, generally male, who would attend (usually several) students in a variety of ways, including cleaning; generally equivalent to a gyp at Cambridge University or a skip at Trinity College, Dublin. 

  • A person sent out to gain and bring in tidings; especially, one employed in war to gain information about the enemy and ground. 

How often have the words knock on wood and scout occurred in a corpus of books? (source: Google Ngram Viewer )