Eggnog has European roots. Some experts say that eggnog comes from the English word "noggin" and began as a mixture of sherry and milk. The drink was modified in Colonial America, where the wine was replaced with rum, which was commonly referred to as "grog."
"Noggin" refers to a wooden mug in which the egg drink was enjoyed in various English taverns. In the 1800s, eggnog was made in large quantities as a social drink, especially around the holidays as it is today. Sometimes it is mixed with whiskey, rum and sherry, and it comes in a variety of different flavors.