during breastal masterbation the male ejaculates under the breasts and she leaves it to dry overnight so the following morning when she applies her brassier she gets an extra 'boost' of clevage due to the dried semen holding up the fukkin hoes tittys like a bitch ...
boy 1 : Y a' yo titties bigga thn yesterdii?
girl: I have received a "Boostknocker" BIATCH
boy 2 and boy 3 and boy 7: OWNED BITCH
boy 1004: YEs :)