break off vs knock it off

break off

verb
  • To end a relationship. 

  • To end abruptly, either temporarily or permanently. 

  • To remove a piece from a whole by breaking or snapping 

knock it off

verb
  • To cease doing something, particulary annoying or unpleasant; to desist. 

intj
  • Cease doing something, particularly annoying or unpleasant; desist. 

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