The eggs have sat in the fridge, and now you're not sure how fresh they are! Here's how to tell:
Fill up a a pan with enough water to cover the eggs and set the egg in question in the pan. If the egg lays on it's side, this means the air cell inside is small and it's fresh. If the egg sits upright, it's not quite as fresh but still okay to eat. If the egg floats or bobs on the surface, throw it away.