To enlarge the volume of a substance, thereby increasing the profit when selling such product. Mostly used by lower level drug dealers, employing fiends who cut up coke, increasing the volume of a batch by a certain percentage. An increase in volume without increasing the amount of basic substances leaves you with an inferior product.
Antoine: Aiyo, i got this horrendous nose bleed last night from the white Dukie i got up on 53'rd street.
Peshawar: Man, i told you not to get that stuff from uptown, they always big it up. You should visit my Jamaican friends down south for some crystal clear premium grade stuff.
Antoine: Aight man, hook me up for tonight.