The "a-ok" sign has positive meaning in Britain and in the USA. It's also the internationally-recognised way that scuba divers say to each other "I'm just dandy, thanks for asking".
But in France, the very same hand shape refers to "zero" or "worthlessness", and in Brazil it refers to a part of the body that the sun doesn't often shine upon.

Sun, sand, sea and stripping off: the planet's top spots for baring all... (contains minor nudity)