get it on vs help oneself

get it on

verb
  • Used other than figuratively or idiomatically: see get, it, on. 

  • To engage in a fight. 

  • To have sex. 

  • To hurry up; to get a move on. 

help oneself

verb
  • Used other than figuratively or idiomatically: see help. 

  • To serve oneself, especially to take food or other supplies, rather than wait to be served by another; used to indicate friendly permission or invitation. 

  • To exhibit self-control. 

  • To take something freely; to serve oneself without restraint. 

How often have the words get it on and help oneself occurred in a corpus of books? (source: Google Ngram Viewer )