Here are a couple I heard in the original German:
Bumse Mich Wieder
Bayerische Mist Wagen
Run them through Google translate! (edit: now that I try that myself, I see that Google picks the wrong translation for the second one, so I'll tell you that the common translation for mist is manure.)
The Germans do have a sense of humor, but sometimes you must dig to find it.
My personal fav, though, is
Bikes Made Weird