YSK: When traveling abroad, hand gestures can mean different things in different cultures.
Why YSK: No sense in making the locals mad unless you mean to. In some Middle Eastern countries, a thumbs-up is comparable to the middle finger. A peace sign in the UK is OK if your palm is facing away from you; otherwise, it's an insult. Pointing with your index finger is offensive in Malaysia. An OK symbol is not OK in Brazil, it's that smelly hole you normally sit upon.