burble vs have bats in one's belfry

burble

verb
  • To trouble or confuse. 

  • To babble; to speak in an excited rush. 

  • To bubble; to gurgle. 

noun
  • The turbulent boundary layer about a moving streamlined body. 

  • A bubbling, gurgling sound, as of a creek. 

  • Trouble; disorder. 

  • A gush of rapid speech. 

have bats in one's belfry

verb
  • To be crazy or eccentric. 

How often have the words burble and have bats in one's belfry occurred in a corpus of books? (source: Google Ngram Viewer )