Big breasts

Big breasts (abbreviated BB) is a fetish relating to the size of a female's breasts, particularly a large size. While the word 'big' is used in the fetish's name, it is often meant a far larger size than what 'normal people' consider big.

It mostly manifests itself alone, that is just a super busty female, but it is quite common - especially in comics - for BB to cooperate with breast expansion.