LMAO full form – LMAO (Laughing My Ass Off) is an Internet slang used in chatting to describe something extremely funny. LMAO is used especially in text conversation where emotion/voice tone is not possible to be expressed. It is much easier to write LMO than to write “That really made me laugh” or that was funny.
LMAO history
Started in the early 1990 and now become standard in Internet slang.
LMAO Icon
instead of being written as LMAO people sometimes use emoticons similar to below:
LMAO sample

LMAO related words
LOL = laugh out loud
ROFL = rolling on the floor laughing
Lmfao = Laughing my F*** ass off
LMAO or LOL in other languages
Thai: 555 in Thai pronounced ha, so 555 = hahaha
Danish: g for griner means laughing in Danish
Indonesian: wkwkwk, awokawokawok
https://en.wikipedia.org/wiki/LOL