Brewfest isn't just about racing rams, it's also about drinking! When you have a moment, take this voucher to Belbi Quikswitch. She's near the back of the Brewfest camp. If you can't see her, don't worry, she'll be sure to see you.
In any case, take this voucher to her to get your free Brewfest stein. She'll also be more than happy to handle any and all other Brewfest transactions.