pull teeth vs undertake

pull teeth

verb
  • To do something that is especially difficult or effortful. 

  • To remove teeth, usually because they are diseased or damaged. 

undertake

verb
  • To take upon oneself; to start, to embark on (a specific task etc.). 

  • To commit oneself (to an obligation, activity etc.). 

  • To pass a slower moving vehicle on the curbside rather than on the side closest to oncoming traffic. 

noun
  • The passing of slower traffic on the curbside rather than on the side closest to oncoming traffic. 

How often have the words pull teeth and undertake occurred in a corpus of books? (source: Google Ngram Viewer )