The thumbs up in America means "OK" or "no problem," or something similar; however, in the Middle East this is an insult that has similar meaning as giving someone the finger in the United States.
Giving the peace sign with your palm facing the other person is fine, however giving it with your palm facing you is the equivalent of giving someone the middle finger in some countries.
In some European countries, the thumb signifies the number one, rather than the index finger in American. So when ordering a drink, using your index finger may tell the bartender you would like two drinks.
The hand gesture for "OK" can be taken as an insult in Brazil, Turkey, Italy, Russia and Greece, but means "worthless" or "zero" in France.
Scratching your chin can be interpreted as an Italian way of insulting someone, as well as flicking your front teeth with your thumbnail.
It is important to study dining etiquette so as not to offend the chef in another country. For example, in some countries crossing your silverware over your plate after a meal is an insult or a compliment, just as setting your silverware side by side can be.
