Wisconsin Public Radio just did a piece on the book The Cheesehead Night before Christmas, by Fred Lane and Romey Wagner. (The WPR link is this, and the book is available here.) The book's a rip-roaring scream, from what they report (and see here for video). They worked every possible dialect stereotype into the text from da Pack to boots lined up "side by each" (yes, people actually say that sometimes).
Good as the story is and as much fun as a dialect humor is, the kicker is that WPR's reporter talked about this several times as Wisconsin "ethnic dialect". What we've generally seen happen over time is that ethnic features have become regional — 'come here once' may have roots in the German modal particle mal, but tons of people of many ethnic backgrounds use it in especially eastern Wisconsin. Is this a not-quite-successful reference to that past? Are Wisconsinites now forming a new ethnic group?
Whatever. I know what I want to find under the tree.