A version of "LMAO" with not just 1, 2, 3, 4, 5, 6, 7, or 8 extra Os, but 11 extra Os. "LMAOOOOOOOOOOOO" is used when something is funny, VERY funny. You may feel too excited so much so you will laugh this hard. For something not as funny but still super funny you can say "LMAOOO", "LMAOOOO", or "LMAOOOOO". For something funny though you can just say "LMAO" or "LMAOO", but "LMFAO" and "LMFAOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO" can work too.
Hahahahahaha!!!!!!!! I died laughing LMAOOOOOOOOOOOO!!!!!!!!