lmfsoo Share definition Flag Laughing-my-fucking-socks-off-outside. Also, a dumbass way of typing 'lmfao'. Me - Let's make dirty snow-people! I wanna see some giant snow-tits! You - LMFSOO! lmfsoo by TylerGthatsme February 10, 2010 0 0 Get merch Get the lmfsoo mug. Buy Now — $32.95 See more merch