ding-dong vs warning bell

ding-dong

noun
  • A sound made by a bell. 

  • A penis. 

  • An idiot. 

  • A woman's breast. 

  • An attachment to a clock by which the quarter hours are struck upon bells of different tones. 

  • A fight, an argument; a set-to. 

adj
  • Closely fought. 

verb
  • To ring with two tones, like a bell swinging back and forth. 

warning bell

noun
  • A bell rung to warn people of a danger. 

  • A problematic or alarming aspect. 

How often have the words ding-dong and warning bell occurred in a corpus of books? (source: Google Ngram Viewer )