I suppose I'll give in and answer this as well.
My first job, I worked for this crazy old man who owned a media production company. Everyone called him Mr. Wizard because he could do just about anything. The dude was a genius.
Well, after tagging along with him for 3 or 4 years, I picked up all his little secrets. So I was "Mr Wizard number 2" to all the people that knew us. That was no fun to type, so it was shortened to mrwizardno2. Incidentally, that was and is my first AOL screenname, and probably will continue to be my only one.
Luckily I no longer work with him, as he was quite a hazard to my health. I had quite a few experiences where I consider myself lucky to have made it through alive.
And thus, you now have the story of my teenage years and why I chose a stupid screen name.