forking vs prong

forking

noun
  • division into forks 

prong

noun
  • A branch; a fork. 

  • A thin, pointed, projecting part, as of an antler or a fork or similar tool. A tine. 

  • The penis. 

verb
  • To pierce or poke with, or as if with, a prong. 

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