1. Even if not learned through experience, it can also be learned through critical thinking. One could take a moment to ponder why someone is checking the eggs and could easily arrive at the conclusion they're checking for broken ones.

2. Or they could open their mouth without thinking much and say something ignorant to a stranger in the grocery store

3. Or they can demonstrate the greater depths of their ignorance and make a post about it on a social media platform showing they had time to figure it out but couldn't despite it being on their mind the entire time.

Sadly, much of our random interactions and popular public discourse are driven by #2 and #3

You can also learn without parents, when you all of a sudden have your hands/shopping cart/shopping bag/car full of raw egg.

It's obvious the first time you get a carton of eggs home and find a cracked or missing egg, or have thought for two seconds about the notorious fragility of eggs.

I feel like the poster might have been aware of the actual purpose but still wanted to spread a little enjoyable sillyness by comparing it to movie scenes where a money briefcase is checked out.