Humerous moment in grocery store....

I did some shopping at Pick'nPay today. I walked over to the egg stand and observed a little Chinese lady standing over a box of 18 eggs. She was prodding the top of each egg with her index finger, going through the eggs one by one.

Curiosity got the better of me and I asked, "Excuse me Maam, but what are you doing?"
She looked up at me with a grin and replied, "Checking.... this one good.... this one bad", as she moved her finger from one egg to another.

Realizing that her English was not very good, I did not ask her how she determined the good eggs versus the bad eggs by tapping each one with her finger, so decided to google this when I got home.
Guess what! I found nothing on google regarding this! The Chinese lady obviously knows something we don't!!