Leet first came around in the early unset rooms to get around filters.

1337 fr|57 c4|\/|3 4r0und 1n 73h 34r1j un537 r00|\/|5 70 g37 4r0und f|173r5.

But sewiously, 1337 is really pwitty awesome.

*6u7 53r|0u51j leet(lol) 15 r3411j pw17+j 4w350|\/|3.

Here's a guide:

4 *6(i made that up i think) c d 3 f g h **1{except in a word that could use both i and l then it's |(i made that up too)} )(i made it up) i'll be back in a sec. to finish this