This is partially true....eggnog is related to various milk and wine punches that had been concocted long ago in the "Old World".
In America, rum was used in place of wine and in Colonial America, rum was commonly called "grog", so the name eggnog is likely derived from the very descriptive term for this drink, "egg-and-grog", which turned into eggnog. At least this is one version.
It's kinda like fruitcake....you either like it or don't.
Classic Christmas Eggnog
12 egg yolks
5 cloves, whole
4 cups milk
4 cups cream
3 cups light rum
1+ ¾ cups sugar
2+ ½ teaspoons vanilla essence
1 teaspoon cinnamon, ground
¾ teaspoon nutmeg, ground
In a saucepan over low heat, blend the milk, cinnamon, cloves and half a teaspoon of the vanilla essence. Keep stirring while mixture heats, and remove from heat just before boiling point.
In a bowl, mix together the sugar with all the egg yolks. Make sure you whisk them well so that they're light and fluffy.
Gently and a little at a time, pour in the milk mixture while continuing to whisk.
Transfer mixture back into your saucepan over a medium heat while continuing to stir. Keep stirring until your eggnog mixture starts to resemble custard. Never let the mixture reach a boiling point!!
Pour and strain the mixture into a jug, making sure to remove the cloves. Stand jug in the fridge for an hour or two.
Gently stir in the cream, light rum, remaining vanilla and ground nutmeg. Put back into the fridge overnight.
Serve in cups with a little extra ground nutmeg, cinnamon or baking cocoa sprinkled lightly on top.