A curious thing happened on the way to the brewery this week that had homebrewers lining up and down Brooklyn’s Fulton Street with heavy jugs of beer in tow. Kelly Taylor and Sonya Giacobbe, the husband and wife duo behind New York City’s KelSo brewery, invited over 80 homebrewers to come and take away five gallons of wort for their eponymous IPA.

In partnership with local homebrew shop Bitter and Esters, KelSo marked the twelfth day of Christmas—known on the Christian calendar as the Epiphany—by providing a mystery batch of beer to the city’s thriving homebrew scene. Keeping details to a minimum in the lead up to the event, participants were not told what kind of beer to expect, but to bring their equipment and prepare themselves to ferment just about anything. According to Kelso’s Chris Cuzme, the participants are free to do whatever they like with the unfermented beer (known as wort) that the brewery gave away. The catch? They have to bring their concoction back to the brewery to share.

Next month, participants will trek back to the brewery with finished product in tow. What these kitchen counter chemists come up with is anyone’s guess. Brooklyn-based homebrewer Sam Burlingame? is using his haul to make a split batch of Berliner Weiss, while Mary Izett, author of Speed Brewing, got home to get the sous vide machine up and ready for a kettle-soured brew.

With just over 160 fermenters bubbling away, what other creations come back to KelSo’s brewery in February is anyone’s guess.

Brian O’Connor is a deputy web editor at Foreign Affairs. He writes about politics, culture, and drinking. Follow him @briantoconnor_