No Lie Silver Pendant

Tibetan Tongue Pendants
"Tashi Delek!"

Sticking out the tongue was once a common form of formal Tibetan greeting which has not yet completely disappeared:
"In 1727, when Tibet was invaded by Dzungars, the practice of Bon was again prohibited. Many Bon Lamas were executed at this time, and the Nyingmapas were persecuted as well. When meeting, the Dzungars would force the Tibetans to show their tongues. They thought that if the tongue was a light color, it proved that the person was neither a Bonpo nor a Nyingmapa.  It was believed that the tongues of these peoples had turned black or brown due to numerous recitations of mantras."  ~ http://www.khandro.net/langnlit_toc.htm

I have not found the original source for the quote above yet.  While traveling in Tibet I heard that it was supposed to show that your tongue was not blue and therefore you were not a demon and did not tell lies.