A plummer Share definition Flag when a person bends over and the crack of thier ass is visible over the back of thier pants , it is said to be a plummer man , tha t fat guy needs a belt, whenever he bends down he treats us to a plummer A plummer by Colt45MaltLikka May 28, 2006 0 0 Get merch Get the A plummer mug. Buy Now — $32.95 See more merch