A term used to describe any female of any age that does nothing but bull shit.
Guy: you wanna chill
Chick: Sure Okayy!!!
Guy: we still gonna chill
Chick: no im sorry ive got to go shopping with my mom and friends.
Guy: Damn shes a BSB
John: I know man, but that's the life and motivation of a BSB so what do you expect.
Tom: You're right. BSB's...smh