failbrat Share definition Flag A fangirl who keeps trying to make herself look good but her arguments come up short. That girl is such a failbrat. She give the only good reason for like the Jonas Brothers is that they are "HAWT" failbrat by AlisaGirl1990 August 23, 2009 0 0 Get merch Get the failbrat mug. Buy Now — $32.95 See more merch