Doomkopf
Idoit, Dummy, Total Imbecile, person who just screwed everything up. It sounds like a German cuss word or something. Its what you call someone when nothing else seems worthy of their complete stupity, idiocracy, impudence, ignorance, worthlessness, wrong place wrong time-ness.
"I just ran over your cat" fred said. "YOU... YOU... DOOMKOPF!!!!!!!!!!