If someone is Asian and are generally or stereotypically a really smart person, and you ask them a question and they answer it wrong or blank out for a few seconds and say "yeah?", then you are allowed to call them a "stupid Asian". Also, if they do something that is obviously stupid (e.g. jumping off the stairwell while trying to fly...even if they're just joking), than you can also call them a stupid Asian. If they've done something not even stupid or wrong, than you shouldn't call the Asian person a stupid Asian, because seriously, that's like calling this blond haired person a "dumb blonde", if they won a Nobel Prize. It's just stupid...
You: Hey dude...so uh, how 'bout that weather today...?
You: Ugh, you stupid Asian!
You: Mr. _____, what is the answer to 4 + 4?
Asian: Ooh; I know!
You: ...well, what is it?!
You: Ugh, no you dumbass; eight! Agh, you're such a stupid Asian.
Asian and You: *laughing*
((There are some more examples, but I'm too lazy...))