Pavel Chekov enjoying a glass of vodka.
Vodka is an alcoholic beverage from Earth, originating in Russia. It is one of the ingredients used in making a Moscow Mule. (DS9: "Once More Unto the Breach")
Vodka was Pavel Chekov's drink of choice. While drinking it aboard Deep Space K-7, he was asked by Scotty when he was going to "get off that milk diet?" Adding that in Scotland, vodka is referred to as soda pop. (TOS: "The Trouble with Tribbles")