Have you eaten rice today?

So...
In one of my english books it says that in some countries they don't say "Hello", but "Have you eaten rice today?"
So I ask you:
Have YOU eaten rice today?

Uh, in Chinese you do say "Hello," but "have you eaten?" is also a polite and acceptable way to greet someone (usually someone you are familiar with). The word for rice just happens to be synomynous with food.