Saying "Ma'am"
It used to be a common courtesy to refer to olden women, like teachers, mothers, or grandmothers as "ma'am," but now that seems antiquated and unnecessary. It was a common phrase in the South, but in countries like Europe, "ma'am" hasn't been used in decades. You'll only catch Oliver Twist saying it in the old movies.
Blasting The AC
Americans love their air conditioner. But if you've ever summered in Europe, you know that Europeans really don't. A fan or two in one room is really all they need, while over in the States we're content to rack up the electrical bills and sit in an ice box all summer.