bust ass vs get one's ass in gear

bust ass

verb
  • To work hard, especially when trying to achieve a goal. 

  • To fart. 

get one's ass in gear

verb
  • To exert effective effort; to get going; to get moving; to start producing. 

How often have the words bust ass and get one's ass in gear occurred in a corpus of books? (source: Google Ngram Viewer )