The popular holiday beverage containing sugar, milk, and eggs is eggnog. It is a rich, sweet drink traditionally made with milk or cream, sugar, and beaten eggs, often flavored with nutmeg, cinnamon, or vanilla.
Eggnog developed from older European milk-and-egg drinks and became especially popular in the British American colonies during the 18th century. Rum was commonly used because it was less expensive than imported brandy or wine, while plentiful farm dairy products made the drink practical to prepare.
In the United States and Canada, eggnog is strongly associated with Christmas and is usually sold seasonally from Thanksgiving through the end of the Christmas period. It may be served without alcohol or mixed with rum, brandy, bourbon, or whiskey. Commercial versions are typically pasteurized, while traditional homemade recipes may use raw eggs, so food-safety-conscious cooks often use pasteurized eggs or gently cook the mixture.
A common mix-up is assuming eggnog must contain alcohol; alcoholic spirits are optional, not essential. Another related drink is the Tom and Jerry, a hot cocktail based on eggnog that became popular in the 19th century.