I may have deeply offended an American chef yesterday when he was telling me about cooking the perfect Thanksgiving dinner and mentioned sweet potatoes. I think I stopped ranting about how they were essentially the devil's food about 20 minutes later (this was at the end of a very long evening)
They're not potatoes and shouldn't be allowed to masquerade as such, la.
Americans also eat something called 'candied yams' with their dinner. I've no idea what these are, but they sound utterly disgusting.