prudsack Share definition Flag balls that have ceased to drop Matt Greene from Corona del Mar high school's prudsack look more like a hacky sack than marbles in a bag. (cuz he's gay) Matt Greene's a prudsack. prudsack by MR.Nasty June 11, 2006 0 0 Get merch Get the prudsack mug. Buy Now — $32.95 See more merch