jackass vs shepherd's clock

jackass

noun
  • A male donkey. 

  • A foolish or stupid person. 

  • An inappropriately rude or obnoxious person. 

  • A jack and an ace as a starting hand in Texas hold 'em. 

  • A kind of bootleg liquor. 

verb
  • To behave very obnoxiously. 

shepherd's clock

How often have the words jackass and shepherd's clock occurred in a corpus of books? (source: Google Ngram Viewer )