On 26th June 1963 John F Kennedy said to the crowd in West Berlin: “2000 years ago the proudest boast was: “Civis Romanus sum.” Today in the world of freedom the proudest boast is: ‘Ich bin ein Berliner!’
Colloquially saying ein Berliner as opposed to Berliner makes the statement mean: “I am a jelly doughnut!” but in this context his audience understood that he meant to show his solidarity to the citizens of West Germany so there was hardly a pause before they cheered wildly!
The joke: “I went for a Chinese the other day. He didn’t do anything, I just went for him!” is an illustration of the low level of ambiguity involved in the understanding of the words that JFK spoke that day! 😉