(n.) While egg whites might show up in sours or fizzes, any drink with a whole egg could be considered a flip, a category that has been floating around since the 17th century. The early versions involved heating sugar or molasses-sweetened beer until the sugar caramelized. Sometime in the 19th century, eggs got added to the mix. The modern version usually works like this: a base spirit, a whole egg and a sweetener, shaken and served with grated nutmeg. Eggnog may be the most famous drink to come out of this category, but the formula allows for a host of variations.