What is 5 over 8 of an egg mean?

Well, darling, 5 over 8 of an egg simply means you're dividing an egg into 8 equal parts and taking 5 of those parts. So, if you're making a recipe and it calls for 5/8 of an egg, you better get cracking and figure out how to measure that out! Just don't go trying to slice an egg into 8 perfect pieces, that's just egg-streme.