You know that fallacy where you assume that others know as much as you, for one reason or another? (At least, it's better to assume that people know something than otherwise.)
I recently linked my sister to [youtube]http://www.youtube.com/watch?v=wCgx8zM3woQ[/youtube] and she surprisingly told me that she only ever heard of the obvious American stereotype... I mean, it's not like I've traveled much, but probably due to my extensive reading of random stuff on the net I found that I only haven't heard of about a couple (Polish and Puerto Rican)...
Then again, ignorance can indeed be bliss...