[Serb5150]

The Germans knew what he meant, mistake and all. I doubt any of them thought he was actually saying "I am a jelly donut", although a Berliner is indeed a pastry.

Lots of places in Germany have food items named after them, depending on where the dish originated. For instance, a Hamburger is both a resident of Hamburg AND something that White Castle serves.

[pganini]

The correct usage is:

Ich bin Berliner.

If you add an "ein", it means a jelly donut.