keister vs sit upon

keister

noun
  • The anus or buttocks. 

  • A suitcase or satchel. 

verb
  • To conceal something in one's rectum 

sit upon

noun
  • buttocks, bottom 

  • small, portable cushion for sitting on 

verb
  • Synonym of sit on (“block, suppress, hold back”) 

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