Remember "Ich bin einer Berliner" ?
No. He said "Ich bin ein Berliner" He called himself a jelly doughnut.
Actually, that's an urban legend.....JFK was announcing the USA's support for West Germany after the Commies erected the Berlin wall at East Germany. He allegedly made a grammatical error by saying "Ich bin ein Berliner," which, according to legend, refers to a jelly donut, not Berlin. This is a play on words because in fact, Kennedy's statement was grammatically correct.
In German, the indefinite article ein is not necessary when speaking of a person's profession or residence but is used when speaking in a figurative sense as Kennedy did. Since he was not from Berlin but only declaring his support with its citizens, "Ich bin Berliner" is perfectly acceptable. And while those that live in Berlin do refer to themselves as Berliner; jelly doughnuts are called Pfannkuchen (pancakes) in and around Berlin----only in other areas of Germany do they call them "Berliners".