Well, when I was making a Reddit account, I decided that I need a nice username.
After a while of thinking, I came up with SirSteveTheGr8. Now, I don't use Reddit anymore, (I deleted my account, for feck's sake) but the name stuck. At least until I ran across a site which doesn't allow usernames that long. So then I just shortened it to just SirSteve.
Steve isn't my real name btw. I just liked the way it sounded.