mbug said:
Make your own eggnog. Store bought stuff is nothing like the real thing.
I've only seen it cold. It needs to sit for a couple of days in the fridge after being made for the flavors to deepen, so it's cold by necessity.
I've used brandy, but traditionally, it's bourbon. (After all, the "nog" in eggnog is truly nog.) However, it tastes perfectly fine without any alcohol. I prefer it without, since alcohol so easily overwhelms my tongue. I despise all things rum, so I never use it.
As far as I can tell, men seem to like it more than women. I hate the store bought stuff. I only like it when I make it myself without the nog.
There are two types of eggnog: the custard kind and the raw egg kind. Even though I have my own chickens and have little fear of sickness from my eggs, I prefer just bloody cooking the thing. If you buy eggs from the store, I definitely recommend cooking it. It's like a pudding with the consistency of cream. After the custard cools, you fold in whipped egg whites, which gives it a frothy, airy texture to complement the taste. I store it in glass milk jars.
My father and grandfather like it in their coffee. :3
Edit: Eggnog must have nutmeg, preferably freshly grated nutmeg. It must. It will taste like a regular creamy custard without the nutmeg. I also like cinnamon and the tiniest hint of clove, but that's just me.
Watch the Good Eats episode that one person provided. It truly is all you need to know.