grass up vs snitch

grass up

verb
  • To betray by informing on. 

snitch

verb
  • To inform on, especially in betrayal of others. 

  • To contact or cooperate with the police for any reason. 

noun
  • A ball used in the sport of Quidditch. 

  • A thief. 

  • An informer, one who betrays his group. 

  • A nose. 

  • A tiny morsel. 

How often have the words grass up and snitch occurred in a corpus of books? (source: Google Ngram Viewer )