bang piece Share definition Flag n. a girl whose only usefulness is to get a guy off. The sex is for male relief and there is total lack of affection in the act. When Brie Ann was cranky or otherwise wouldn't put out, there was always Sylvia, his bang piece. bang piece by Richard Black June 10, 2005 0 0 Get merch Get the bang piece mug. Buy Now — $32.95 See more merch