Wisconsin has its own dictionary, a little book you can buy at souvenier shops. I gave a copy to one of my Japanese friends at school so she could understand us Wisconsin folk. In Japan they had learned proper English so when they got to the US weren't they surprised!We speak a lot of broken German dialect here too, even if we aren't German.

Here's the most common:
http://www.homestead.com/cameronwis/WisDictionary.html
Ones I say most are Ain-a-hey, Ain-so, uffdah, and yahhey. The only misconception is the cheddarhead thing. Not many Wisconsinites call themselves cheeseheads, just the hicks and football fans, and honestly I can't distinguish between the two.