In all seriousness, the notion that Germans lack humor stems from the times when English and American people last got in contact with Germans in larger numbers: In and after WW2. Allied propaganda did paint the Germans as humorless (because they can't be totally evil if they still have humor), and after the war, living in Germany was not exactly fun.
In reality, Germans have a lot of humor, its style being similar to the British, but a lot of it is hard to translate or is based on experiences that non-Germans don't share, like old German TV shows.