Use of German words in american TV-series?

As I like to watch American TV-series in their original language (and thankfully, Swiss TV provides the opportunity), I've recently observed that many of them like to throw in random German words regularily. Some series even seem to make some sort of running gag out of it and use at least one German word per episode. (In general, these are series who celebrate geeks.)

First, has anyone made the same observation?
If yes... any idea, why they do it? Is German that popular (among geeks at least)?

I've been also wondering about the use of "uber" in English, which seems to be widespread. Where does that come from? Since when do people use it?