nitty-gritty vs nubbin

nitty-gritty

noun
  • The core or essence of something; the gist. 

nubbin

noun
  • The clitoris. 

  • A small protuberance, bud, bump, or knob. 

  • A stub, especially a stub of undeveloped corn or fruit or nipple. 

How often have the words nitty-gritty and nubbin occurred in a corpus of books? (source: Google Ngram Viewer )