"Many people will argue that it started with the popular game Counter Strike, but X's def. is the most correct. According to "The Hacker Crackdown" by Bruce Sterling, it was an invented language used to confuse FBI and NSA sniffing programs during Operation Sundevil, when the government placed "wiretaps" on the Killer server to find hackers. Used extensively after the E911 document scandal and the theft of Korn 78 and other UNIX programs by AT&T. Google "Fry Guy", "Terminus", "Gail Thackery", "Acid Phreak" and "Phiber Optik" for more information. Discontinued among true hackers thanks to encryption engines and PGP keys."
Now used by sad individuals, with no grasp on the english language.
You are not 'l337', you're just a stain on the underwear of life.