LOL, LMAO, and ROFLMAO

If LOL means "laughing out loud" then what does "LMAO" mean?
I see that in many jokes I receive. Thanks for telling me.

Sparrow, that means "Laughing My Ass Off!"

And while we're at it here, I should tell you another one you may sometimes see. ROFLMAO... That means "Rolling on the Floor Laughing My Ass Off."