Stfuhammer Share definition Flag verb.What you do to someone when they don't shut up. A hammer, screwdriver, nail, nailgun, screw, or pliers may be used. Tom kept talking so Matt stfuhammered him repeatdly in the dick. Stfuhammer by Jokig May 16, 2011 0 0 Get merch Get the Stfuhammer mug. Buy Now — $32.95 See more merch