Interesting. It's sort of the opposite when Thais ask if you have eaten already because if you answer "not yet" it is common for them to offer you something.
The Scottish response to 'not yet' is usually something like 'well it seems foolish to have ventured out in that case', obviously delivered in the local dialect.
Though I have extracted one dinner from an Edinburgh man who deploys the phrase, but that was probably because his ( English ) wife had put it on to cook earlier!
