Eating noodles in Japan? Be sure to slurp them. Not only is this OK but it is expected.
When eating rice in Asia, never put your chopsticks into a bowl of rice in an upright vertical position. This is the way rice is offered to the dead and also imitates the way incense sticks for the dead are burned. Also, don't pass food directly from your chopsticks to another pair of chopsticks. If you want to pass food, place it on the person's plate. Passing from chopsticks to chopsticks is a Buddhist funeral custom where the cremated remains are passed from family member to family member.
Tough for Americans but in Russia, better table manners are displayed by keeping your knife in your right hand and your fork in your left hand. Also, rest your wrists on the table edge.
Show good manners in Nepal by waiting to be served and, if eating at a private home, ask for seconds. When eating with a group, no one leaves the table until the entire group has finished eating. If you must leave the table early, apologize and instruct those at the table to 'please, eat slowly'.
You'll be insulting the cook in Portugal if you ask for salt and pepper or any other type of condiment that is not already on the table or served with the food.
When dining with other people in France, discuss the meal's financial arrangement before going into the restaurant. Talking about the bill over dinner and/or splitting the check is considered extremely unsophisticated.
Be prepared to share your meal from a single dish when eating in Ethiopia. Also, don't expect to be handed any cutlery. And meat dishes are usually eaten last. So don't head for the meat first and don't eat quickly which can be interpreted as greed.