Your Eggs Can Swim!
Egg carton dates are unreliable, but this farmer’s method of identifying egg viability is not: carefully lower an egg inside a full glass of tap or bottled water. Does the egg sink and stay sunk? Then that egg is fresh, my friend! Does the egg float about?
Then you can safely throw that egg away without hesitation (and here’s some science for you: the egg floats because of gas build-up as a result of the decomposition process).