chum up vs pal up

chum up

verb
  • To be friendly toward (with or to) someone, especially in an ingratiating way; to form a friendship (with). 

pal up

verb
  • to become friends with. 

  • To form a small group. 

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