arse vs sit upon

arse

verb
  • To be silly, act stupid or mess around. 

noun
  • A stupid, pompous, arrogant, mean or despicable person. 

  • A person; the self; (reflexively) oneself or one's person, chiefly their body; (by extension) one's personal safety, or figuratively one's job, prospects, etc. 

  • Used in similes to express something bad or unpleasant. 

sit upon

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

noun
  • buttocks, bottom 

  • small, portable cushion for sitting on 

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