What president said something wrong in German?

The legend went that John F Kennedy said "I am a jelly donut" when he was speaking in Berlin when he was trying to say "I am a Berliner" because Berliner Pfannkuchen means jelly donut in German and is usually shortened to Berliner in some parts of Germany. However, in Berlin, that phrase isn't used, instead jelly donuts are referred to as Pfannkuchen in Berlin. So, really the jelly donut myth is simply that, a myth.