But I don't think Americans, overall, are fat or stupid, though we do like our guns. And we seem to be far more expressive (emotional) than others.
But then, I grew up in America and I'm a mutt (as are many others here), made up of five nationalities (Dutch, Irish, English, German, and Cherokee Indian) and that's the fun of living in this country.
I don't own a gun (yet) and I don't consider myself stupid and I'm not fat. So what national stereotype is that? Maybe I need to do some nationality shopping.