Pazx is sorta like a backronym. Backronym = word that became an acronym but it was already a word. Except it's not an acronym.
I just made it up one day (PaZx) when I was playing this game (Atomic Tanks :D) on my Dad's computer. I then always said it was the first letter of my name, first of the alphabet, last of the alphabet and the X because I liek it, but that's really not true. I just needed an explanation.