lmfao- an acronym used by many internet addicted people for they are too lazy to type it by itself. Lmfao are the begining letters of "laughing my fucking ass off".
Since most of the people who use this acronym are addicted to internet and spend most of their time sitting at a desk, the meening of lmfao has changed from "laughing my fucking ass off" to "laughing my fat ass off".
fAtSO#1: i just shit'd ma pants.
nerd#1: we know ur ass is fat dude... just say lmao... or nothing at all...
nerd#2: Lmfao! oh wait nvm...
"insert name here": lmfao
me: ur fat.
"insert name here": when did i say i was fat!?