SOS vs look out

SOS

noun
  • A children's game in which players take turns to place S's and O's on a grid, collecting points by creating an "SOS" sequence. 

  • The conventional Morse code call made by a ship in distress. 

look out

verb
  • To be vigilant and aware often as an imperative to alert a person to danger. 

  • To find by looking: to hunt out. 

  • To be facing (used with "on"). 

  • Used other than figuratively or idiomatically: see look, out. 

How often have the words SOS and look out occurred in a corpus of books? (source: Google Ngram Viewer )