Used to express extreme excitement almost as a form of a gasp, but not always in the form of laughing your ass off.
In a chat:

Anon1: Someone lick meh.
Person1: *licks anon*
Person2: Eww. Don't. You'll get anonitis!
Person3: Anonitis? LANMAO.
by Leanne and Dan March 25, 2008
Get the LANMAO mug.
means penis hair
use as an insult etc. or an alternative of "asshole" in singapore
bruh u damn lanmao eh
by luo_guan January 27, 2020
Get the lanmao mug.