One of things that surprised me when I reached the US was finding that no one under the age of 13 know how to use a knife and fork, and those older barely.
Most sort do this weird thing of using their fork for both job, quite an accomplishment when you consider how difficult it is to cut bacon with a fork.
Eating with your mouth shut? Apparently no one is supposed to talk in the US unless they have their mouths stuffed with food.
I suppose they are so in love with food here, that they find it sexy to see it spewing from the mouths of those around them.
Anyone who's been here from England will have been through the truly odd experience of having Americans unable to understand half of what you are saying. Simple words take four or five attempts to get through.
It's not stupidity - although not many are blessed in the brain department - it's simply they can't understand words that aren't spluttered with mashed potatoes, burgers or crisps.