mouth off vs sass

mouth off

verb
  • To talk impudently, especially to one's superior. 

  • To complain or otherwise express oneself in a loud, immoderate manner. 

sass

verb
  • To speak insolently to. 

  • To talk, to talk back. 

noun
  • Backtalk, cheek, sarcasm. 

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