beat it vs whack off

beat it

verb
  • To masturbate, usually a man of himself. 

  • To leave; to go away. 

  • Used other than figuratively or idiomatically: see beat, it. 

whack off

verb
  • To masturbate. 

How often have the words beat it and whack off occurred in a corpus of books? (source: Google Ngram Viewer )