noun - cliquey slang, characterized by acronyms, misspellings and replacement of letters with numbers and other symbols. The phenomenon originated in occasional use by hacker culture and, much like everything else on the Internet, poseurs and wannabes have destroyed its original charm through overuse and audacity.
l337k1dE: m r3dy 2 pwnz sum n00bz
C@L0vr: kimn, pwd nermel
l337k1dE: u r teh haxx0red
l337k1dE: roflmao u suk
shakespeare: Methinks you people are complete idiots.
Most of the entries on Urban Dictionary fall into the category of garbage-jargon.