The Colonel's birthday party becomes a perfect opportunity for getting the real painting of the Fallen Madonna with the Big Boobies back from Herr Flick of the Gestapo, and substituting it with the forgery that was made earlier. The plan is to not invite Herr Flick but make sure that he hears about the big Binge - a traditional feast with genuine Bavarian dances featuring girls dressed as the Hitler Youth - so that he will have to come. In the meantime, René and Edith are supposed to walk into the office of Herr Flick and substitute the real with the fake. Of course, they fail - which means that Herr Flick now both has the fake and the original plus a second forgery, which he commissioned on his own in order to have money for his marriage with Helga after the war... (thetvdb.com)