an instrument used to ground up marijuana so it can be rolled. Often a coffeegrinder can be used to work on this. a bud buster is truly a coffee grinder, but put to great usage. Grab some marijauna, chuck it in grinder, give it some energy, and voila, freshly ground buds(easy for rolling). I bet Proctor & Gamble would not have thought their coffee grinder would-be used for busting buds(hence the expression)!