BBG Share definition Flag Big Breasted Girl. Typically to describe a lady with breasts that are popping out of her clothing. Tim:"Whoa look at Amy! , She's such a BBG! Mark: "I KNOW RIGHT! Really wanna stuff my face in it!" BBG by Facts4Life January 10, 2019 0 0 Get merch Get the BBG mug. Buy Now — $32.95 See more merch