Global hand gestures have different meanings -- travel website Cheapflights will help you make sense of them all in this 'Global Guide to Hand Gestures.' The many gestures you think are ubiquitous are actually controversial in some countries.
Do you think a "thumbs up" is a sign of approval? Think again, because in Latin America and East-Indian countries it's seen as an "up yours." And what I believed to be the universal sign for world peace, only means peace in North America; the 'V' sign signifies contempt of authority in the UK, Australia and New Zealand! Likewise, in European countries the "double horn" gesture, or what you may know as "rock on," symbolizes an unfaithful wife.
You should definitely keep these tips in mind the next time you travel abroad, because with the flick of a wrist, you can either get yourself some new friends or get yourself into some serious trouble.