rock the boat vs stir up

rock the boat

verb
  • To disturb the status quo or go against rules or conventions, as in an effort to get attention. 

  • I'd just jump in and fix it, but that's not my job, and I don't want to rock the boat. 

stir up

verb
  • To arouse or excite (passion or action). 

  • To move or disturb slightly; to make turbid. 

  • To mix (ingredients) by stirring. 

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