'Hammasi' was a Tarn beverage and a rather potent alcoholic brew.
History and specifics
The recipe for hammasi is considered to be a secret by the Tarn. Data had come across the recipe several years prior from an unnamed source. One of the ingredients is fermented blood of a creature rather similar to a tiger on Earth. The bartender must allow the blood to congeal under the sun, drain the remaining liquid, then mix it with the fermented milk from the Yaktu. There was another step in the process that fascinated Lieutenant Commander Data, however Captain Jean-Luc Picard had decided to interrupt the conversation at this point. Picard had asked Data to work with Guinan to come up with a reasonable facsimile of hammasi for Harna Karish in 2367. The facsimile had a strong gagging effect on Picard. Hammasi is served in a gilded horn. Karish closed his eyes and ceremonially let several drops fall on the floor before drinking. The beverage was also enjoyed in large quantities by Admiral Garu Jord. Data stated that hammasi had a curious taste and was starting to like it. (TNG novel: The Forgotten War)