I found this on a Wiccan site:
Egg divination is known by many names (oomantia, ooscopy, and ovamancy). It dates back to ancient times, and most every culture has practiced it in one way or another. It can be used to determine the sex of an unborn child, and to find out if someone has been cursed by the evil eye.
All you need is an uncooked hen egg which can be bought at the grocery store or at the dairy. To find out if the pregnant mother is going to have twins, she (or the person who is doing the fortune) should rub and egg on her belly for a few minutes, then break the egg open into a saucer. One yolk indicates single birth, two yolks means twins, and so on. If the yolk is spotted with blood, it indicates a bad omen, either a miscarriage or complications during childbirth.