Egg Nog is a creamy, rich drink that is very popular in the UK and in North America. Typically, it is served over the Christmas holidays.
Generally, it is made from eggs beaten with sugar, milk or cream, with some kind of alcohol added either right in the mix, or upon serving directly into the glass.
The alcohol is usually rum, but in the American South (especially in New Orleans) it is often Bourbon.
Commercial Egg Nog is usually UHT pasteurized to give it a long shelf life under refrigeration. It is sold in cardboard or plastic cartons and jugs, and in some areas, in plastic bags. It will appear in stores in the lead-up to Christmas, and disappear shortly after New Year.
Bottled Egg Nog with alcohol already in it does not need to be refrigerated until the bottle has been opened.
You can also buy Egg Nog flavoured syrup now to add to coffees, milk shakes and smoothies.
Egg Nog cannot be frozen because it will separate and have a funny texture upon thawing.
Egg Nog began being made apparently in the 1700s, and was well known both in America and in Britain at the time. But in England, only the upper classes would have drunk it at first -- the ordinary people in the cities wouldn't have trusted any of the milk they had access to at the time. It was more popular in America, where people were closer to farms they knew and milk they trusted.
In England, they mixed it with Brandy, Madeira or Sherry. But in America, Rum was more popular, as the spirits used in England were heavily taxed by the time they arrived in the New World.
"Even the cows are celebrating for Christmas. Sheffield Farms report their dairy herds are giving eggnog by the quart, mixed to charge the merry bowl. Apparently the cows have added to their feed 'sugar and spice and everything nice,' including a touch of rum flavoring. This eggnog which you can order through the milkman (or having no milkman, a local branch of the company) combines rich cream with eggs, sugar, nutmeg, and the flavor of Jamaica rum. A smoothly blended pleasant drink as it is without spirits to use just as it comes from the bottle. No beating to do, no additions to measure in, nothing to do unless you wish to add a 'stick of dynamite' from your liquor shelf. This ready-made eggnog must be ordered three days in advance and is available throughout the holiday season, December twenty-third to January first, inclusive." -- Paddleford, Clementine (1898 - 1967). Food Flashes Column. Gourmet Magazine. December 1945.
Egg Nog literally means eggs inside a small cup -- apparently. There doesn't appear to be any general agreement on how to spell Egg Nog -- Eggnog (all one word) seems to be equally as valid.