Fresh Dwarven Brewfest Hops

Fresh Dwarven Brewfest Hops provides a buff which converts your mount into a Swift Brewfest Ram mount, normally associated with the Alliance. Only available to the Horde. Duration: 1 hour.

Source
Fresh Dwarven Brewfest Hops is purchased from the Horde Brewfest Token vendors and  for a cost of. These are only available to the Horde, and are only available during Brewfest; the Brewfest Tokens required to purchase them disappear when Brewfest ends.

Use
Using a Fresh Dwarven Brewfest Hops puts a buff on your character which converts your mount into a Swift Brewfest Ram. The buff is on you, not on the mount; if you switch mounts, the buff is still active. The duration of the buff is one hour.

Achievement
Use of this item satisfies the achievement if you have riding training. You do not have to have a mount, nor use a mount, nor have a mount actually converted; the achievement procs as soon as you use the hops. This item is a cheap way to easily proc this achievement.