We are all guilty of throwing eggs away because they are (on paper) out of date but it isn't always necessary that they get chucked out just because the sell-by date has passed. As long as your egg has been produced to high food safety standards and has been bought from a major supermarket in the UK, then you can use the simple float test to check whether the egg is good to eat or not. Most often it will be good to go, even if it is passed the official use-by date.
So to check, fill a glass with cold water and place your egg into it. If it sinks to the bottom and lays flat on its side, it is very fresh. If it is a few weeks old but still good to eat, it will stand on one end at the bottom of the bowl. If it floats to the surface, it is no longer fresh enough to eat.
The egg in the image was technically two weeks out of date, however, it sank in this glass. We therefore cracked it and had delicious scrambled eggs for breakfast. Please make sure to test your eggs before chucking them away!