That person would happen to be here in ZU longer than you?
I don't remember how long you have to be here, I think you've stayed long enough, you must go in the User CP, and select Edit profile tag. And enter something in the CT box.
After you've been a member for four months, you can change your custom rank to whatever you want, whenever you want. Post count doesn't make a difference anymore, because that method had a tendency to make people want to spam to 1000 posts. I'm looking at you, GoldenChaos.
Question answered, thread locked, and moved to FSQ.