"iTz" is a statement of self-misconception that putting things like multiple x's, MLG, "legit", and "iiTz" in combination for a pseudonym will make one totally badass. Generally, these specimen are annoying prepubescent teenagers, or self-righteous douchebags of an older literal age (versus an older mental age).
Warning: Do not attempt to interact with these species (one specimen might be identified as something along the lines of "iiTz lEGiT MLG pRoO xXx"), as they will often challenge you to a one-verse-one duel. Denial to the challenge will result in a incessant condescending speech explaining (without logical sense) why you are a small cat.
Guy: "Nice game, everyone."
xXiiTz NaZtyy QuiikscopzXx: "Fuck you! I could take your ass any day! Let's go, one-on-one, bitch!"
xXiiTz NaZtyy QuiikscopzXx: "Ha! You pussy, you can't even take me on a one-on-one! You fucking suck! I'm going to tell everyone how much of a fucking loser you are because you back down when there's a real challenge! Faggot!"