curry favor vs slip in

curry favor

verb
  • To seek to gain favor by flattery or attention. 

slip in

verb
  • To include (e.g. a certain word or phrase) into a sentence discreetly 

  • To enter discreetly 

  • To play a subtle pass into someone in a goalscoring position. 

How often have the words curry favor and slip in occurred in a corpus of books? (source: Google Ngram Viewer )