"in the sin of vulgarity, the youths of Israel die, G-d forbid." meaning- these negative words, that we nowadays call negative energy- that comes out of the mouth, spread in the world and cause great harm- "the youths of Israel" refers to the young ones of Israel who may be harmed as a result of that person's vulgar speech. furthermore it was said :"Because of the sin of obscene speech, troubles renew themselves and the youths of Israel die, G-d forbid.- And , "If one corrupts his mouth, Hell is deepened for him." 