IDIOMS

brain fart

(idiomatic, slang) Something ill-considered and said or done impulsively.

Example: 2011, Grace Dent, The Guardian, 8 Jul 2011:
  This is love in the social media age. Candlelight dinner, fine wine, degustation, a lover's face scrunched over a phone screen live-tweeting brainfarts about the relationship to largely uninterested skim-readers.