DuckCorp Dico

Found one definition

1.                 From The Jargon File (version 4.4.7, 29 Dec 2003):
                   
   
   
                   
                     
   DAU
    /dow/, n.
       [German FidoNet] German acronym for Dümmster Anzunehmender User (stupidest
       imaginable user). From the engineering-slang GAU for Grösster Anzunehmender
       Unfall, worst assumable accident, esp. of a LNG tank farm plant or
       something with similarly disastrous consequences. In popular German, GAU is
       used only to refer to worst-case nuclear accidents such as a core meltdown.
       See cretin, fool, loser and weasel.