2 or more more bros. "bru bras" is a untraditional spelling of "bro, brooooo's " which is a play on the phrase "bro, broooo." It's making that "bro, brooo" phrase into a description of a type of human being.
The brubras saw their favorite Youtuber in real life and all started murmuring "Bro, bro, is that..."
by halekyish April 22, 2017