RMFAO Share definition Flag Engrish version of LMFAO...Laughing My F*cking A*s Off. Oh, sank you so belly much for retting me watch Purdue Football. They suck so bad, I was RMFAO! RMFAO by Robster Craws September 23, 2005 0 0 Get merch Get the RMFAO mug. Buy Now — $32.95 See more merch