bumfuck vs sexual union

bumfuck

noun
  • Anal sex. 

  • An isolated place far removed from major cities. 

adj
  • I hate living in this small town in the middle of bumfuck nowhere. 

  • Isolated and neglected, undesirable, or held in contempt. 

verb
  • To fuck anally. 

sexual union

noun
  • Sexual intercourse. 

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