You might see this term in a video of how is twitter free. My research concludes to most probable definition is the following:

L - Laughing

M - My
A - Arteries
O - Out

You find yourself in a FaceBook group chat.
Hey Susan did you see that me-me is sent you?

Yes Geraldine it was delightful! I'm LMAO.

LMAO by sub to Fainted February 16, 2021

Merch

LMAO

Lobsters Making Anonymous Observations

Who wrote this?
Isn't it obvious? Lmao!

LMAO by Hubeebe February 24, 2021

Merch

Lmao

L lick
M my

A ass
O onee-chan
Ofc why would it be anything else

Hey mum What? Lmaooooooooooo

Lmao by PP_lord69 February 28, 2021

Merch

Lmao

L-et M-e A-ssault O-rally, be careful if someone says this to you!

Random creepy guy that likes radiohead too much: "LMAOOO"
girl: "omg why would you say that?"

Lmao by Joseph_2002 March 3, 2021

Merch