When I was stationed in Berlin in 1972-73, many of the locals thought I was a wonderful conversationalist, and that I was amazingly fluent in German. I could understand almost everything perfectly, but my speaking ability wasn't (and isn't) all that great. But I knew one word of Berliner Deutsch, and I learned to use that one word very well: doch. "Doch" is kind of a universal word of attention and affirmation and acknowledgement. The tone with which the word is used, gives it a wide variety of meanings, all of which are very affirming to the other person. Use that one word wisely, and you'll get along just fine in Berlin. Every language needs a word like that.

-Joe-