My name is Zac, and one of my high school friends realized if I ever became a Pro at something, I'd be a "Pro"Zac. We decided I was pretty professional at being myself, and the nickname stuck with me since then, going so far as to have it embroidered on my jacket (by my parents as a graduation gift) and even some teachers knowing me by that name.
On CAG, just 'ProZac' was taken, so I had to alter it a little.