On his sail barge on the way to the Pit of Carkoon, Jabba and his guests had drinks served to them by R2-D2 and other of the Hutt's servants. Jabba had a priceless goblet filled with some sort of green liquid, most likely alcoholic given Jabba's debauched behavior, which he forced Leia to drink.
Leia's Reaction to Drinking from the CupEdit
Given that the cub was half full and encrusted with Jabba's green saliva, it is likely that Jabba took a sip of the beverage before offering it to Leia. For her part, the princess found the Huttese liquor extremely strong and did not enjoy partaking of the drink, as the drool from Jabba's mouth that coated the lip of the glass sullied her lips and tongue.