Phoenetic description of L338, which is L337+1, also known as Leet+1. When one is Leeb, they are just too Leet to be described in conventional terms, thus, a new category of Leetness must be invented. Leeb people are as Leet as everyone else, but have that small extra something about them which makes them Leeb.
Stacy: OMG!! 8 headshots, I R TEH L337!!!!
Dick: I h3adsh0tted 9er peepz, 5tanding on my h3ad! WooTNESS!
Stacy: D1ck IZ TEH LEEB!!!!!!
A screw-up. Leeb is a typo of leet, or 1337, spelled as 1338. Generally, it's made by someone who tries to be 1337 but in their declaration of all that is awesome about themselves involves many an uncorrected typo.