It comes from the super hero from the webcomic Cyanide and
Happiness, who flies down into the scene, wearing a
shirt saying "LF" on it, and promptly says "LOL!!
FAG!!" to the reader/other characters in the comic, and flies off.
"LOL!!
FAG!!"
LF, the abbreviation for lol,
fag, is often used in gaming as a burn or
insult.
