If you want to get wicked on some unsuspecting lowbie players. Go to one of the starting areas. Doesn't matter what faction you are but it does matter class. You would need to be a Hunter. Make sure you have no pet so you can tame one and tame one of the starting animals in the area. Once you do that (flag PvP if on a non PvP server) go "Eyes of the Beast" and start wandering around with the animal acting like one of the flock there. If you are lucky enough a new player will hit your animal and not notice that the animal was flagged and flag themselves in the process.
I was in Northshire on a disturbance call and found a 60 Troll Hunter doing this to the people of Northshire. I then proceeded to gank him since he did not see me behind him.
I did a quick search for this and didn't find anything about it. But I would believe it would be an old Hunter trick, so if it has been posted before I am sorry.