Reposted from my repost of my original post:
Mine is from a group my friends made in high school, back when everyone was obsessed with GoldenEye 64. We all picked numbers, I got 005. When I wanted to change my lame first.last@juno.com email address (to give you an idea of how long ago this was), it hit me to spell it out. I've used it for everything ever since.