Derived from lol but due to overuse loi is to show when something clearly isn't funny.
Person 2 - Loi. /Or Lol (lack of laughter)
Person 1 - Haha did you see such and such tonight, PMSL!!!!
Person 2 - No n00b LOI!
Created to replace "LOL" since most people do not actually laugh out loud when they type it in a message.
Girl #2: "LOI! You're such a slut."
Lois is such a sweet girl, i love her to bits