Used to inform somebody, usually via text message, that they are taking forever to do something. Using the abbreviation implies that you are becoming impatient, thus, can't be bothered with writing the full words out.
Josh: "Yeah, I'm leaving in 2"
Jack: "I wasn't born yesterday, you're probably still washing your hair!"
Josh: "Haha :P"
chatspeak for 'laughing my larynx out'. similar to LOL, ROTFL, and LMAO, but unlike in 'LMAO' and 'ROTFLMAO', the larynx, as opposed to the ass, has a connection to laughter, so although you couldn't laugh your larynx out any more than you could laugh your ass off, LMLO sounds better and doesn't contain any swear words.
Audrey: The one with the unicorn? LMLO!!!!!