I recently read that the meaning of some hand gestures can be very different depending on where you are from.
For example: In the USA it is common to point with your index finger to indicate a place or direction you are talking about. It is also common to bend your index finger to indicate you want someone to follow you. However these are both apparently very offensive gestures in India and some other nearby countries.
I have also heard that the thumbs up and "ok" sign can be offensive in some countries.