Fonzie was an immigrant to Milwaukee from New York. Had the writers decided to give the show more of a true Milwaukee flavor and made the Fonze a Polish or German city resident, could he have been as cool? Would his catch phrase have been "Aiiinnnn'aaa!"?
Completely Unrelated Sidenote
Before writing this post, I Googled the alternate aina spelling of enna. Google wanted to know if I meant to search for Enna Jameson. Amusing.
Postscript
For those of you coming here from outside Wisconsin, ain'a is perhaps the most well known word in a form of speech known as Milwaukee-ese. There, ya learned something today.