Franzl is kind of a nickname that I use in Germany, obviously makes little sense to people in the U.S.
My actual name is Franz-Josef. I use "Joe" while in the U.S., like now, because I don't like explaining my life history to everyone, and because nobody here can pronounce it anyway 
Franzl is just the nickname for Franz-Josef.
(Besides, why Joe and not Frank, say?)
That name caused me quite a bit of teasing as a little kid
The reason my parents called me that is probably because my dad has the same given name...guess that means they couldn't think of anything else
As to the Frank or Joe part....when my parents divorced and my mother and I went to the U.S. when I was 5 years old, my grandpa gave me the choice of Frank or Joe, and I chose Joe, and it's stuck by me ever since. He still uses it, just like everyone else....and I have a strange habit of calling my American grandpa "Opa". I doubt he'd respond to anything else now
