I stumbled across this interesting article from Budget Travel on 15 International Food Etiquette Rules That Might Surprise You. I pulled some of the ones I found most interesting to share with you.

Don’t eat anything, even fries, with your hands at a meal in Chile.
Manners here are a little more formal than many other South American countries. So while it might be the most practical to just pick up those fries with your fingers, don’t do it.
In China, don’t flip the fish.
Although you might be used to flipping over a whole fish once you’ve finished one side, don’t—at least not when you’re in China, especially southern China and Hong Kong. That’s because flipping the fish is dao yue in Chinese, a phrase similar to “bad luck.”
In Italy, drink a cappuccino only before noon.
Some Italians say that a late-day cappuccino upsets your stomach, others that it’s a replacement for a meal (it’s common to have just a cappuccino, or a cappuccino and a croissant, for breakfast). Either way, you won’t see Italians ordering one in a café at 3 p.m.—and certainly not after a big dinner. Do so, and you’ll be instantly branded a tourist. If you need that coffee fix, though, an espresso is fine.
At a traditional feast in Georgia, it’s rude to sip your wine.
At what Georgians call a supra (traditional feast), wine is drunk only at toasts. So wait for those… and then down the whole glass at once. On the upside, the glasses tend to be on the small side.
In Japan, never stick your chopsticks upright in your rice.
Between bites, your chopsticks should be placed together right in front of you, parallel to the edge of the table—and nowhere else. If there is a chopsticks rest, you use it, putting the tips you’ve been eating with on the rest. But sticking them upright in a bowl of rice is even worse: During funerals in Japan, the rice bowl of the deceased is placed before their coffin… with their chopsticks upright in the rice.
Have you broken any of these rules? What food etiquette rule gets broken by tourists the most where you live?