My dad always had vanity plates on his car with the handle "Poo" on them. My dad's sister picked that nickname up from a radio DJ in San Antonio in the 70's named Bruce "Brucie Poo" Hathaway since my dad's name is James Bruce he became known as Poo. To this day there are people that know him only by that nickname. You could call his office when I was younger and ask to speak to James and more often than not the switchboard operator would tell you that no one by that name worked there, ask for Poo and you got connected right a way.
But these people have much more vivid immaginations. Some of them are hillarious. I especially like the "Eat the Kids First" one.