The black guy at work asked me about Polish food

Was wondering if I can recommend any good polish food, said he's never tried Polish food before but liked perogies. I told him that I'm not Polish, I'm German and the food we eat is German not Polish. Guy got mad at me and said "you're obviously Polish", I told him that we Prussians are German and that Prussia was part of Germany. He didn't believe me when I told him that Poland didn't exist until 1918 and that the majority of Poles live in Germany.