I assure you it is very much a real thing i've seen people do, Many of the youth in my ward in church have been doing it and ruining their jaw, It may have started as a joke but the youth are impressionable and stupid. And likely many of the members of this forum (who are roughly the same age) may end up doing the thing as well. It is like when they made those fake ads that you could microwave an iphone 7 to charge it, it was clearly fake but the ignorant fell for it. Or the "cool crystals" post from '08 that had folks mixing bleach and ammonia then blowing with a straw. People are dumb, always assume the worst.