So what does a Frat zog stand for?

fratzog lover said
It was actually the Chrysler employees teenage sons who coined the term "fratzog", when Dad asked them what his symbol should be called.

That's actually not true. As mentioned my Grandfather did this emblem, and my Dad (the oldest) was only 6 years old when the work was done. So the teenager coming up with the name is folk-lore.