A few little things I’ve started noticing it’s pretty difficult to explain to non-Americans:
1) Continuous-spray sunscreen. Seriously. Try spraying yourself down with it in a crowd of Brits some day. They look at you as if you’re wielding a light sabre.
2) The phrase “balls to the wall.” Not the kind of etymology I’m sure I’d even want to be able to explain, actually.
3) Febreze. (“It’s this stuff that you spray on your dirty clothes when they smell really bad… and it makes them smell less bad… and then, you see, you can keep on wearing your dirty clothes for longer.”)
4) The Soup Nazi episode of Seinfeld. That humor seems to be pretty lost on Germans.
5) Come to think of it: Seinfeld.