fire-crotch vs firebox

fire-crotch

noun
  • A person who has red pubic hair. 

firebox

noun
  • A redheaded woman or her red pubic hair. 

  • The part of a fireplace where the fuel is burned. 

  • The chamber of a steam engine, or a steam locomotive, in which the fuel is burned. 

How often have the words fire-crotch and firebox occurred in a corpus of books? (source: Google Ngram Viewer )