I've been leaching long enough, so I figure I would contribute. This trick is really easy. There is a mob in Dragonblight that is immune until somebody starts a quest. Go there late at night or something when nobody is around. AFK attack and enjoy.
The name of the mob is Rothin the Decaying, he is in the cave at the obsidian dragonshrine. I'm not going to bother posting a screen, as there is one here: Rothin the Decaying - NPC - World of Warcraft
If this is a repost I apologize. I didn't see it here so I posted it.
Edited for poor grammar.