I can explain it lonely. A few years back now a hacker language became extremely popular amongst gamers where letters were replaced with numbers and symbols the language was called 1337 (in it's truest form many refer to it as L33T or |33T) the alphabet in 1337 goes a little like this
A - 4
B - 8
C - (
D - |) or D
E - 3
and so on. there are several dialects of the language distinguished by the speed it takes to type theres FPS Haxor (Hacker) and what it generally refered to as standard L337. the language is still used but frowned upon in places like other Forums...(MT especially).

Damn P|-|33|2 7|-|3 |<|\|0\/\/13|)G3