whilst peoplemay think that B.B.B has multiple meanings, it really only has one. the meaning of it is Bumming Boys in the Bathroom. this is mostly used for posh private/catholic school boys. B.B.B dosent have a deeper meaning below bumming boys in the bathroom, it genuinely means that you were shoving you cock into ur friends ass.
Amy: where were you all of lunch?
Jack: oh sorry my friends and i were B.B.B