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.
Tossing brew to a friendly target who is flagged for PvP will cause your character to be PvP-flagged, too.
Item is only available for purchase during Brewfest.