Where does your user name come from?

Hi everyone,
I'm curious to know what's the story behind your user name (or Alias)... There are a bunch of people that use their name (of parts of it) like myself, Albert Porter, GerryM5, Esoler...

But where does user name like Cornfedboy, Garfish, Calloway, Tireguy, SwampWalker (and many many others) come from? Any story behind?

Just curious