1 Monty: Right. Let's get out of here before Colonel Haken and his Nazi goons return.
2 Prof. Jones: But Junior! We must go to Berlin to retrieve my diary. It can lead us to the Grail!
3 Monty: Ich bin ein Berliner, hey?
4 Prof. Jones: You're a doughnut?

2012-01-12 Rerun commentary: This is a reference to John F. Kennedy's famous 1963 speech in West Berlin, during the Cold War, and the mostly apocryphal story that his use of the sentence "Ich bin ein Berliner" was grammatically inappropriate and actually meant "I am a doughnut", rather than the intended "I am a citizen of Berlin". (This story is discussed in some detail at the afore-linked Wikipedia page.)

Language can cause some amusing misunderstandings. As can gestures. And again US presidents are not immune. I remember vividly the day when President George Bush (Senior) visited Australia in 1992. As he stepped off a plane in Canberra, he was "greeted" by a large group of farmers, protesting against US agricultural subsidy policies (which make Australian agricultural exports to the US significantly less profitable to our farmers). President Bush attempted to give the farmers a "peace" sign with fingers held up in a "V" shape, which would have been okay if he hadn't delivered the gesture with the back of his hand facing the farmers, thus forming the incredibly offensive Commonwealth "screw you" sign.