Great thread! I've been asked this question a lot too.
My handle stems from many years ago when a kid in our church gave me a video game to play on my computer. Can't remember the name of the game, but it was fun. You could travel to different worlds, different levels, blow up protecting spaceships and stuff like that. When I quit the first game mid way it asked me to save it with a screen handle. The blowing up of spaceships reminded me of shrapnel flying everywhere, so I was trying to find something to rhyme with it or sound close to it and came up with "Schrack." I thought, "Cool." Since then it has evolved to Schrackman. So yeah, my inspiration came from a stupid computer game. LOL