There's no winning with Americans...
I was in Knightsbridge tube station the other day, and I took a call on my mobile before boarding the train; it just so happened that I was standing near the underground map, whence I saw an American couple, quite old, with baseball cap, back pack and all.
I decided to be a good representative for my country, and tried to help them out; so I said to them:
"Where are you trying to get to?"
At this point, I thought to myself, forget it... Better not to ask them how they intend to get to Holland from Knightsbridge underground station, as they may find it rude. However, I think they read the subconscious, bewildered expression on my face, so the man continued,
"Ah, well you ought to take the Piccadilly line east to Holborn and then take a Central Line back west to Holland Park"
"But it looks much closer if we change at Green Park and Bond Street"
At this point I gave up, and walked off... I really did not want to get into a discussion about how the Tube map is not to scale or geographically accurate. Not only that, but they would also spend longer waiting for trains. Surely, they would realise that a man with a local accent, in a suit is not going to direct them wrongly, particularly given they were in T-Shirts and Shorts...