National Whiskey Sour Day is observed on August 25 each year, celebrating the iconic whiskey cocktail that has been around for over a century and a half. This unofficial holiday encourages people to enjoy a whiskey sour, which is made with bourbon whiskey, fresh lemon juice, and simple syrup, and may include a dash of egg white. The cocktail’s history dates back to at least the 1870s, with claims of its invention by Eliot Stubb in Peru in 1872. The whiskey sour is recognized as one of the official cocktails by the International Bartender Association and is listed in their Unforgettables category. Variations of the drink include the Boston sour, which incorporates egg white, and the New York sour, which adds red wine. To celebrate, enthusiasts can visit their favorite bar or learn to make the cocktail at home, often sharing their experiences on social media with the hashtag #NationalWhiskeySourDay.