Based off a conversation I once had with a genuinely very intelligent Korean classmate. He'd already been living in the US for quite a while.

Chiaki: So... is a cheeseburger just a burger with cheese?

Twogami: ...Yes? Yes, that's exactly what that is???

Chiaki: Okay, good.

Twogami: How did you not know that?

Chiaki: ...We're done with this conversation.

And so they never talked about it again. But Twogami could never look at Chiaki without remembering it after that point.