highway robbery vs overboard

highway robbery

noun
  • The act of robbing a traveler on a public road. 

  • Said of excessive or exorbitant prices. 

overboard

adj
  • Outside of a boat; in the water. 

adv
  • Over the edge; especially, off or outside of a boat. 

  • Excessively; too much. 

verb
  • To throw over the edge of a boat into the water. 

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