anus vs keister

anus

noun
  • The lower orifice of the alimentary canal, through which feces and flatus are ejected. 

  • An impolite, unpopular, or unintelligent person. 

keister

noun
  • The anus or buttocks. 

  • A suitcase or satchel. 

verb
  • To conceal something in one's rectum 

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