Orb of Deception, or "There's a Horde in Stormwind"

(Lethon)

Very fun, very expensive. Goes for 100-800 gold on the AH. Best drop rate is from Lethon (31%), a dragon that is hard to kill with a full level 60 raid group.

The orb drops occasionally from other things (mobs, chests, bosses), but nothing close to as often as with Lethon.

The Orb of Deception makes you look like the other side for 10 minutes, and has a 30 minute cooldown. Like Savory Deviate Delight, it only changes your appearance, nothing else, but it's still pretty fun. Purely an entertainment item -- no help whatsoever in battle, fooling the other side, or bolstering your stats.