How do you speak English?
This Dialect map quiz
of the United States has been going around for a while, and I got to thinking about how, even after the Internet and Television has messed with local accents, significant amounts of English are still shockingly localized. There's the infamous Soda/Pop/Coke debate, but around Boston it's still pretty easy to call sweet, fizzy drinks Tonic. Milkshake only occasionally means what non-Bostonians think it means up here (Milk, Ice Cream, Syrup); what other places call a milkshake is a Frappe. It's also fairly common to pronounce the "r" in "idea", especially if you're from (or have roots in) Vermont or Rhode Island (I-de-er, if you're wondering how that works). It's also very fuh-stra-ting to deal with difficult people, rather than fruh-stra-ting. A bunch of roads feeding into a single, circular road is a Rotary here, and just about nowhere else.
It's also entertaining when it comes to some of our odder city names. Haverhill is "Hay-vrill", not "Hav-er-hill, Worcester is "Woost-er" not "War-che-ster".
I think the one that got me the most was that soft-rubber-soled shoes, worn casually or as part of athletic activity, are only called sneakers in the northeast. I never had a reason to think that wasn't universal.