BG Dirt Share definition Flag A excessive amount of prepubescent hair that garners one's upper lip and looks amazingly stupid. Man A "Yo, you got some BG dirt, son. Shave that shit." Man B "Fuck you son, it's manly." BG Dirt by Aljosa Buttkisovic July 12, 2006 0 0 Get merch Get the BG Dirt mug. Buy Now — $32.95 See more merch