Don't Want No Zombies on My Lawn

[Traxex84]

So I saw this guy today which is very odd, because this achievement and endless mode never made it to live; they were scrapped from the beta a month or so before release.

Achievements - Game Guide - World of Warcraft

Anyone heard of or know about this? I am going to guess it was done via an exploit or some type.

[Elektropop]

My guesses:
1. That guy have found some weird trigger that triggers that achievement.
2. A GM gave him that achievememt for some reason.

[Fadelol]

Are you sure it is not meant to be ingame? Either way, I'll make a post about it sometime later tonight explaining how to get it(got it myself a few days ago and remember how).