I think you have the letters out of order. It's actually LMFAO.
It can mean any of the following:
Laughing my f-ing ass off.
Lauging my freaking ass off.
Laughing my fat ass off.
Laughing my freaking *** off.
Inbd mean "It's no big deal" in text language.
BTW means By The Way in text language
in text language ttfn means ta ta for now
Inbd mean "It's no big deal" in text language.
defo
RUS in text means "are you serious".
who you speaking to
y=Why
question?
Thinking of you
times