Hand gestures that seem positive in the United States can get you in big trouble elsewhere in the world.
It is decidedly not OK to make this sign in Brazil, Germany, and Russia. In those places, the gesture crassly evokes a certain body part. Like opinions, everybody’s got one.
Although Americans make liberal use of the “rock on” horns at heavy metal concerts (and Longhorns games), in places like Italy and Argentina, it’s how you call a man a cuckold.
You might be wishing for good luck, but flashing crossed fingers in Vietnam, where they’re said to evoke an image of female genitalia, is incredibly offensive.
Hitchhikers and attaboy addicts should keep their thumbs to themselves in places like Greece and Australia, where this gesture essentially says “Up yours,” just less politely.