Pump-Nut Share definition Flag adjective- 1:When a man feels like his scrotum is bigger than it really is. 2:When a man get a sudden burst of inexplicable courage to do something overly stupid. If more people carried guns then the idiots with guns wouldn't feel so pump-nut!!!! Pump-Nut by MandiniA August 9, 2012 0 0 Get merch Get the Pump-Nut mug. Buy Now — $32.95 See more merch