brain fart vs unconcern

brain fart

noun
  • An instance of absent-mindedness or forgetfulness. 

  • Something ill-considered and said or done impulsively. 

unconcern

noun
  • Lack of interest or care; indifference or apathy. 

  • Freedom from worry or apprehensiveness; insouciance or nonchalance. 

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