Black Market Auction House
This item comes from a loot card from the World of Warcraft TCG. It places a large flag in an enemy corpse with a thumbs down. It is awesome in PvP (oh, who am I kidding - it is awesome everywhere).
In Warlords of Draenor, this item will be added to the new Toy Box feature and no longer take up a bag slot. You will be able to "use" the item straight from the Toy Box interface. The Toy Box will be account-wide and therefore so will this item.
This TCG item is obtained via redeeming the "Owned!" loot card from the WoW:TCG expansion, "Drums of War." In Mists of Pandaria, the item also became available through the Black Market Auction House.
As always, be careful in where and who you buy from. Stick with reputable websites like eBay and WoWTCGLoot.