From Halopedia, the Halo wiki
Zantelle is a sparkling alcoholic beverage served by humans. During an ONI training exercise at UNSC Recreational Facility 6055-NA-A on October 14, 2553, Olivia-G291 was offered some by Spencer Hume. Unknown to Olivia, the drink had been laced with nicothiotal, a fast-acting form of Babble Juice. Hume was an investigative journalist, working with Dark Moon Enterprises operative Ota Gallo, attempting to gain information on the SPARTAN-III program in order to undermine ONI.