Autumnal Acorn Ale

Autumnal Acorn Ale is the October brew from the Brew of the Month Club.

Source
This is only available to members of the Brew of the Month Club, which can only be joined during Brewfest.

All members of the Club get a free sample of the brew in their in-game mail at start of October. As this happens to be during Brewfest, your sample will be mailed to you once you buy and hand in a new membership form, should you have not bought it during the start of Brewfest in September. Should you want more, your local Brew of the Month Club Brew Vendor sells it in stacks of six till the end of October.

On the first of October, members receive the following in game mail:

Effects
Drinking one of these will create an Empty Brew Bottle that can be targeted and thrown. It also gives the chance of gaining a  buff. There are three forms of this  buff. The first will summon a Woodland Squirrel that will have hearts over its head similar to Mojo (companion) and follow you around for a short time. The second form will summon a Woodland Squirrel which will then come over to you and hit you in the head with an acorn before running off. The final form will summon a Woodland Squirrel, but it will just run away. It is possible to have multiple Squirrels up at one time.