browneye vs bung-hole

browneye

noun
  • The anus. 

bung-hole

noun
  • The anus. 

  • A hole in a vessel, such as a cask, that may be stopped with a bung. 

verb
  • To have penetrative anal sex with. 

How often have the words browneye and bung-hole occurred in a corpus of books? (source: Google Ngram Viewer )