In many countries, including the United States and Australia, the thumbs up gesture means “good” or “terrific.” In parts of the Middle East and Asia, giving a thumbs up to someone is the equivalent of giving them the middle finger in the U.S. The OK sign, with the thumb and finger forming a circle, also is offensive in many Asian countries as well as Brazil and Germany, although in Japan it represents money.
More facts about international gestures:
In some places in Tibet, sticking your tongue out is a kind, welcoming gesture.
Even a simple smile can be misunderstood. In many Asian countries, smiling can be taken as a sign of embarrassment or anger. Prolonged eye contact also can come across as rude or invasive in Japan, China, Korea and Thailand.
The “come here” gesture made with the palm upward and the index finger curled, is used only to call dogs in the Philippines, and it signifies death in Singapore.