onanism vs pocket pool

onanism

noun
  • Masturbation. 

  • Ejaculating outside the vagina during intercourse; (the performing of) coitus interruptus. 

pocket pool

noun
  • The act of manipulating one's genitalia through a trouser pocket; masturbation. 

  • A variation of the game of pool. 

How often have the words onanism and pocket pool occurred in a corpus of books? (source: Google Ngram Viewer )