99 Whiskey is a slang term for a particularly high-quality American whiskey. It was first used by American soldiers during the Vietnam War to refer to the high-proof (99 proof) whiskey issued to them by the military. The term has since become more general, and is now used to refer to any high-quality American whiskey.
99 Whiskey is typically made from corn, rye, or wheat, and is aged for a minimum of two years in oak barrels. This aging process gives the whiskey its characteristic amber color and smooth flavor. 99 Whiskey is often enjoyed neat, on the rocks, or in cocktails.