How significant are the German references on the show?

No other country has been mentioned that much on HIMYM. I was just wondering if anyone knew why they keep having so many German references. Do CC have some special relationship I haven't heard of? au is it all just a coincidence?

● Victoria goes to Germany
● Barney has sleeps with German girls
● Ted mentions Bertolt Brecht
● Robin considers sleeping with German guys (even for a joke)
● For Halloween Mike dresses as Hänsel
● Barney uses German words
● Heidi Klum was on the show
● Barney wears a shati that says: "Die neue Wohnung"