Actually, it is not just the mainlanders who asked this
question. The ang mohs also because they can't tell us apart from
Korean or Japanese.
In fact, I was asked this question too, that was like so long ago,
like 1990, here in Toronto. When I replied that I am Chinese, one
HongKonger retorted "no, you ARE NOT chinese, you ARE
Singaporean!!!".

edit to add : to the world, Chinese means from China (HKG included)
