cahoots vs shotgun wedding

cahoots

noun
  • Collusion or collaboration to nefarious ends. 

shotgun wedding

noun
  • Any similarly reputedly forced partnership, between people, organizations, components, or concepts. 

  • A wedding in which the bride is already pregnant. 

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