If you have an accent in America (and experience of other places) you hear or are told things truely worthy of imbeciles on a regular basis. No, Americans don't have a corner on the market on ignorant citizens, just on those who don't realise "It is better to remain silent and be thought a fool than to open your mouth and remove all doubt."
I'm going to post some of those things here that I come across personally that make me stop and wonder how some people can walk and chew gum at the same time...

I hear variants of this on a regular basis. (These are also certain to end a date before it starts...and yes I hear them from women my age & older!)
1 "Ooo, your accent is like so cool. Say something Irish!"
2 "Do you dance like that guy from television?"

This one I heard last year when explaining that I don't celebrate Christmas because I'm a Witch. I had to put it up here as it is so priceless...its from the owner of a yoga centre who was in her 50's...and Jewish too!
- "Why should it matter if you're a Witch? That's what's so nice about Christmas. It's the one holiday that people of every race, creed, color, and sexual orientation can come together in a spirit of peace and love to celebrate the birth of Jesus. It's such a shame that some people ruin it by making it all about being Christian y'know."