busta 9 Share definition Flag To shoot another by using a 9mm or similar weapon such as a Glock in a gangster fashion (i.e. holding sideways and/or in cold blood). Id better get that money by friday or ima busta 9 in yo ass. busta 9 by T Bourke February 7, 2007 0 0 Get merch Get the busta 9 mug. Buy Now — $32.95 See more merch