How people inside the metropolitan Minneapolis/St. Paul area refers to the rest of Minnesota.
A nickname for New York City. Gotham City is a fictional city used in DC Comics, but it is said to be modeled after NYC.
"Smog Angeles" is what many San Diegans call Los Angeles, the rival city to the north.
The Ill Mill is a nickname for Milwaukee used by the younger crowd. It's more often used in an endearing way than a derogatory one.
Around the world people call them Buffalo wings. In Buffalo they're just "wings."