Dear Urban Legends:
I have heard and read from several different sources the story that John F. Kennedy made a major German language blunder in his famous "Ich bin ein Berliner" speech in Berlin, Germany. The story goes that he should have said "Ich bin Berliner" ("I am a citizen of Berlin"), and that "Ich bin ein Berliner" really means "I am a jelly doughnut." (A "Berliner" is in fact a type of jelly doughnut made in Berlin.) One of my German instructors even claimed this is true, and I once saw it published in a major American magazine, although I forget which one.
Several years ago when I visited Germany, I found myself having drinks with a German journalist who struck me as fairly intelligent, so I asked her the question. She said that it is certainly not true. President Kennedy said the phrase absolutely correctly, although possibly with a thick American accent. It seems that the German language is simply not that trivial — it has subtleties that very few non-native speakers grasp. She said that if President Kennedy had said "Ich bin Berliner," he would have sounded silly because with his heavy accent he couldn't possibly have come from Berlin. But by saying "Ich bin ein Berliner," he actually said "I am one with the people of Berlin." This is her exact translation as best I can remember it.
I believe, although someone would have to verify it, that President Kennedy actually didn't know German very well, if at all. He had a German journalist translate the phrase for him, and that journalist coached him at length on exactly how to say the phrase.
Your friend, the journalist you met in Germany, was right on the mark. Notwithstanding reports to the contrary in venues as prestigious as the New York Times and Newsweek magazine, this is truly The Gaffe That Never Was. Experts say Kennedy's grammar was flawless when he uttered those words on June 26, 1963. The phrase was translated for him by a professional interpreter.
Parenthetically, it's true that in some parts of Germany the word Berliner can just as well denote a certain kind of jelly-filled pastry as a citizen of Berlin, but look at it this way: if I were to tell a group of Americans that my editor is a New Yorker, would any of them really think I'd confused him with the weekly magazine of the same name?