Matador Network's site has some really awesome pages on how to offend people of various cultures.
In the spirit of fairness, here's MY LIST of things you can do to immediately piss off Americans overseas.
1. Ask us if we are from New York.
For Christ's sake, people, there are OTHER CITIES in the US besides New York City. In my entire time in Europe, every time I said "I'm American" I would get "Oh you come from New York!" For a little variety, it would be nice if you just included "LA and/or SF" once in a while.
2. Tell us you love some American movie/sports star.
This would also come up when they found out I'm American. People overseas would suddenly blurt out "Oh I love Michael Jordan", or "Oh Brad Pitt is such a good actor." I never understood the point of this...
Are they assuming that I live next door to Michael or Brad and that I'll just tell them this next time we get together to play golf?
3. Assume we all love to eat at the Buffet.
Yes we Americans are fat especially compared to the rest of the world, but that doesn't mean we want to eat the Buffet EVERY DAY. During my first week in Tokyo, my entire group took me to the different buffet restaurants EVERY DAY for lunch. It got to the point where I gained more weight in Tokyo than I ever did in the US.
4. Assume we're all just language idiots and speak to us only in English
Sometimes when I'm in an overseas place, I will attempt to speak to people in their native language. That goes usually ok, until they find out I'm American. At that point it becomes just English. This drives me NUTS! Are they just implying that we're so stupid that there's no POINT in even trying to speak a foreign language??? It's probably true, but it would be nice if they just let us practice a bit ...
5. And finally when we you ask guys "How are you doing?" .. actually answer back.
Let me be perfectly honest. When we ask this question, we really don't care how you guys ACTUALLY are doing. We do this because we merely want to sound more caring than typical Eurotrash who just say "hi". But we just want to hear you reply back "Fine, thanks" so we can get on with our day. There's NOTHING that pisses us off MORE than when some moron stops and ACTUALLY starts telling us about their day. The first time I was in Europe, I made the mistake of asking this to a convenience store clerk. She proceeded to tell me about how she just broke up with her boyfriend of 10 years because he cheated on her with another man, her brother.... THAT was a little bit too much for a first conversation "how are you doing?"