JFK Was a Jelly Doughnut

According to historians, John F. Kennedy may have (accidentally) called himself a jelly doughnut.

In 1963, JFK addressed a crowd of millions in Berlin, Germany. On a last-minute decision, he said the final words of his speech in German.
He ended it with "Ich bin ein Berliner" (I am a Berliner). Ein Berliner can either mean "a Berliner" or "a jelly doughnut."
Another problem is that a native-speaking German would ommit the ein and simply say "Ich bin Berliner".

So did he say he was from Berlin, or simply a jam-filled pastry?

Funny what you learn while reading a German travel guide.