During the GOP primary this year the insults were flying but one candidate tried to stay above the fray. As a result the only insult directed at him was the way he ate a pizza. Different parts of America have their own standards for how to eat the local delicacies but what about when you are abroad? The rules of the table can change there as well.
Thanks to our Japanese daughter-in-law we have learned several no-nos when eating in Japan. The long chopsticks are for serving food. You do not pass food to another's chopsticks using your chopsticks. Chopsticks should not be stuck in your rice while you eat something else. They should be set down parallel to each other on a holder next to your plate. One thing you can do in Japan that is not so much acceptable in the US is slurp your noodles from your bowl of broth. Eating in a noodle shop in Japan produces a lot of strange noises.
An article I found at Independent Traveler.com gave a glimpse into what could be some major faux pas in other countries. For example don't eat with a fork in Thailand but don't eat without one in Chile. Don't cut your pasta in Italy (although someone commented later that her relatives said only a peasant twirls their pasta).
When in doubt, look around you at how the locals are eating. In tourist areas, you are usually forgiven your trespasses but if you want to endear yourself, ask someone like your server or tour guide to give you proper etiquette instructions. Eating like a local is a big part of the travel adventure.
Oh, and when in Japan remember that another person will continue to refill your sake. It's a polite gesture and you are expected to do the same. Just be careful how much you sip because you will never hit bottom. Don't ask.