In Iraq, it is traditionally an obscene gesture, equivalent to the use of the middle finger in the Western world.
So that's why people started shooting at me in iraq!
In the UK, specifically north-west England, a single handed thumbs up sign can be used as a farewell or greetings gesture between young males. In situations where acquaintances may see each other briefly and unexpectedly, but are unable to communicate otherwise (e.g. whilst driving past one another, or through a glass window) the thumbs up signifies a gesture of recognition. It is also often used as a replacement for a more traditional "wave" goodbye when parting from one another. A less common variation is the use of a brief two handed thumbs up gesture made close to the body.
Pretty sure we dont...
Reminds me of that advert where the English guy goes to Brazil but can't speak portugese or whatever it is there speak. He goes into a café and buys something, he sits down to eat it, the chef looks over and the guy gives him the OK sign (Divers), then everyone in the café just stops and stares at him :P
America's secret weapon?