cheddar curtain n. the divisions real and imagined that separate Wisconsin from neighboring states, especially Illinois. Also cheese curtain. Editorial Note: This term is parellel to Orange curtain, cotton curtain, and other, similar terms. (source: Double-Tongued Dictionary)
Further reading
Among biologists, a frog’s croak is known as an advertisement call. It’s a male frog’s way of making himself known. A Wisconsin listener says children in her area learn that this sound is jugarum, jugarum. Poet and editor Willard Espy...
David from Matthews, North Carolina, grew up using the term cheese toastie for a type of grilled cheese sandwich. Cheese toasties are familiar in Ohio, Indiana, and Illinois, particularly around the cities of Decatur and Springfield. In the UK...