Right, I've just asked Sean if he can think of anything that I do that strikes him as being particularly American or odd... I didn't expect his answers to be quite as numerous or readily available. Anyway, here are a few
The way I say "mirror" <-- "mir" as opposed to his "mirr-or"
Holding a door open for a person still 20 feet back from its entrance.
Waitresses saying "you're welcome" at restaurants. Me: Thank You
Waitress: You're welcome
Sean: Why do they always say that?
The fact that Americans will go out for a big meal, order the biggest, most fattening thing on the menu, then ask for a diet coke.
My love of dipping ALL foods in some sort of sauce (ranch, bbq, honey mustard, teriyaki, sweet and sour, ketchup). He thinks it's being fussy.
Commercials after the opening scene on tv shows.
I'm sure there are other, more personal things I do that he finds odd, but those are probably my own strange tendencies, and not the traits of most Americans!