brain fart vs woolgathering

brain fart

noun
  • An instance of absent-mindedness or forgetfulness. 

  • Something ill-considered and said or done impulsively. 

woolgathering

noun
  • Indulgence in idle fancies or daydreams. 

  • The gathering of fragments of wool torn from sheep by bushes, etc. 

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