fap vs wank off

fap

verb
  • To masturbate. 

intj
  • To indicate that someone (normally the speaker) is either masturbating, or inspired to by sexual arousal. 

  • Pornography. 

noun
  • A session of masturbation. 

wank off

verb
  • To masturbate. 

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