I can't decipher this one fully, but
- Green Bay Packers fans are called Cheeseheads and some wear hats pretty much like the cows above
- Green Bay Wisconsin is in dairy country
- Brett Favre was their star longtime quarterback wearing number 4 - there was some controversy about his retirement, then coming back to play for other team (I don't know details)
- i don't know reference to the steaming pie
