Bang From Behind. When a girl has a decent body, but her face isnt that great, you would consider her a bang from behind so you dont have to see her face.
Person 1 - "That chick is not very attractiveman..."
Person 2 - "Ya she's definatly a BFB"
Acronym for "bad for business," meaning something/someone that would affect you and your crew in a negative way. The business always comes first and we don't want to do anything that's bad for the business.
Waking up at a fraternity house after sophomore year is BFB.