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From Unmariowiki

L33t is a language used by the users of MarioWiki. To use it, the user must replace all E's in the english with a 3, O's with 0 etc. L33t also has its own words, like "pwn", "ROFL", and "teh". Mario has used L33t to communicate with the cannibalistic users of MarioWiki. Luckily, he escaped in time. It was also once used by the Foreign Legion.