booster
"The booster" is what is left when you get down to the last 2 inches of malt liquor in a 40 ouncer, preferably Olde English 800 (better known as "Eight Ball").  By the time you get down to the booster it is usually warm, which only serves to make an already unpalatable beverage taste even worse.  Despite the nastiness of the booster, it must be consumed to avoid ridicule by one's peers.
Hey you donkey, are you gonna drink that booster or are we gonna have to put a skirt on you and buy you a box of tampons?