We had a guy who delivered propane to us. His name was Bob.
He used to check for gas leaks with a cigarette lighter.
I called him "Crazy Bob." -- When your name is Bob, and you have a nickname, there's something terribly wrong.
And if your name is John Wayne
Anything, your life will not be a pleasant one!
And that, succinctly, is my theory about nicknames. By the way, my name isn't Bob. That's just my Nickname.
Bob