Gah! I had the comment mostly typed out and tabbed out and it was gone. Alas, here we go.

Once I was in London (your London, not our fake one here in Canada) riding a bus. There was an empty window seat, so I asked the young lady "is this seat taken?" She looks up and me an scowls, clearing picking up what she perceived to be an American accent or turn if phrase and says: "it's not for Americans." I reply, "but I'm Canadian!" fully expecting it to end there. But to my surprise she says, "oh, in that case" and slides over to the window.

In Germany, I've gotten into vigorous arguments with Germans over the proper adjective to use to describe where I'm from. See, in German, the adjective "American" describes anyone from the continents of North or South America. So when I tell them I am not an American, they usually respond with "yes you are." Much debate follows, usually with beer involved.

Speaking of beer. I was in Stuttgart for an open source hacker meeting a while back. After spending the day around a conference table and whiteboard, we head to the bar. The Germans in our group are ordering beer by the litre, in very large steins. When the server comes around, I ask for one as well, and she says: "most Americans find out beer pretty strong. Would you perhaps like to start with a half litre?" to which I naturally reply "But I'm Canadian!". She just goes "oh, I'll bring you a litre."

There are many more such examples. :)