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1.
Silently laughing my ass off.

Generally used in text messages or IM's where the recipient can obviously see you are not physically/vocally laughing; therefore, slmao had to be implemented.
*You have 1 New Message from "Nerd"*

-"Dude, did you hear what DL just said?...slmao..."
by Zac Huntley April 09, 2008
 
2.
Seriously laughing my ass off.
Look at that cheese.

Slmao.
by Leeeeeeeeeerrrrrrrroooooooy October 26, 2007