roflmffo Share definition Flag an acronym meaning "rolling on the floor laughing my fucking face off" rarely used. 1: OMG d1d u z dat guyZ h4t??!!##@ 2: ya fo sho mah negr0. ROFLMFFO. (what he actually did: -.-) roflmffo by uber1337zorZorOMG January 28, 2009 0 0 Get merch Get the roflmffo mug. Buy Now — $32.95 See more merch