dumbfuck Share definition Flag when someone does something really stupid, thats what you call them Natasha, 'OMG JORDAN JUST TRIPPED OVER HER BAG!' Kate, ' Haha... what a dumbfuck!' dumbfuck by natbat2212 May 18, 2016 0 0 Get merch Get the dumbfuck mug. Buy Now — $32.95 See more merch