knocker vs watermelon

knocker

noun
  • A critic; one who disparages. 

  • A person who knocks. 

  • A person who knocks (denigrates) something. 

  • One who defaults on payment of a wager. 

  • A woman's breast. 

  • A large cockroach, especially Blaberus giganteus, of semitropical America, which is able to produce a loud knocking sound. 

  • A large, boulder-shaped outcrop of bedrock in an otherwise low-lying landscape, chiefly associated with a mélange. 

  • A device, usually hinged with a striking plate, used for knocking on a door. 

  • A mechanical device in a pinball table that produces a loud percussive noise. 

watermelon

noun
  • An environmentalist with socialist leanings. 

  • A pinkish-red colour, like that of watermelon flesh (also called watermelon pink). 

  • A project that is presented as on schedule when it actually has parts that are falling behind. 

  • The fruit of the watermelon plant, having a green rind and watery flesh that is typically bright red when ripe and contains black pips. 

  • A plant of the species Citrullus lanatus, bearing a melon-like fruit. 

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