Aldebaran whiskey

"It is... it is... It is green."
 * - Data in 2369

Aldebaran whiskey was a strong, green alcoholic beverage, favored by Guinan, who kept a bottle behind the bar in Ten Forward. It was a gift from her friend, Jean-Luc Picard.

In 2369, Data served Montgomery Scott the drink of Aldebaran whiskey, although he was unsure of its characteristics beyond its color. Scotty found this beverage quite satisfying and drank most of the bottle himself, although he shared a couple of glasses with Picard. 

In 2371, Quark discovered an empty bottle of Aldebaran whiskey in his brother Rom's room that was taken from Quark's "private stock." 

Several barrels of Aldebaran whiskey were kept in storage in several of Deep Space 9's cargo rooms. 

Background information
The green drink seen in is another "tip of the hat" to the green drink seen originally in "By Any Other Name", and is most likely Aldebaran whiskey.

External link
Aldebaran-Whiskey アルデバラン・ウィスキー