Smmfda Share definition Flag An acronym for shaking my mother fucking dumb ass. an advanced way to say smh or shaking my head. bro you actually lost the game, smmfda. Get to the objective or we will lose, smmfda. Smmfda by Dab'angelo June 2, 2019 0 0 Get merch Get the Smmfda mug. Buy Now — $32.95 See more merch