Some oddities that aren't so odd in Rhode Island and South east MA but I don't see around the country.
Vinegar, preferably white and not malt, goes on french fries. Never, ever, put gravy on them like I've seen in NV.
Coffee syrup for making coffee milk and coffee cabs. The syrup is similar to what chocolate syrup is for chocolate milk but I've never seen it anywhere else. A "cab" or "cabinet" is ice cream, milk and syrup. A malt is that plus malted milk.
Lobster that has been frozen might as well be fed to the pigs because only fresh lobster is acceptable.
The bellies of the fried clams are the tasty part. Clam strips are horrible since they are basically just fried batter.
Vinegar also goes on chow mein and chow mein sandwiches. Fried noodles are what is covered by the chow mein.
Chourico goes into everything. Spaghetti sauce, clam boils, and many other dishes that a little spicy sausage will perk up.
As the Chicago poster said, if you dig your car out of the snow bank you own the spot for at least a few days. Chairs, tables, milk crates, etc. will "hold" that spot and pity the jerk that moves them.