It might be bad manners anywhere else in the world, but in Tibet poking out one’s tongue is the customary way to welcome people. The tradition dates back to the 9th century during the time of a vicious Tibetan king known as Lang Darma, who had a black tongue.
The Tibetan people feared that King Darma would be reincarnated so they began greeting each other by sticking out their tongue to prove that they weren’t evil. The tradition continues today and is often accompanied by the person placing their palms down in front of their chest.