I see thereäs not enough understanding on both sides. Mainland Chinese do not actually understand modern European history and Germans do not actually understand modern Chinese history... leading to unnecessary poking each other at the most fragile part of belly.
"Nanjing Massacre" does not poke a joke about the recently inflated but yet still fragile national pride of mainland Chinese, instead it is real bad... it infuses intense hatred into mainland Chinese towards Japanese (its people, its culture) which is already part of the national education program in mainland China. In this historical event, the Japanese army arrived Nanjing were the villain, and killed an unconfirmed number of Chinese people some in very brutal way. The actual number of victims were never confirmed and in a published book about studies of the historical photos of this "Nanjing Massacre", there were lots of potential "photoshopped" photos as suggested by the author. After all, the hatred planted by the Japanese themselves or by the US propagandists who first used the term and published films about it during WWII have been serving really well to destabilize the region, almost ruling out the possibility of collaborating between Japan and China up until today.
It is definitely a taboo topic if you are in a table with Chinese (regardless of where they're from) and Japanese, especially during a business context.
On the other hand, an average Chinese may only know that Hilter is a famous villain in modern history - of course should have killed quite some number of people, end of the story. But they never know and actually never care to know the killings were allegedly committed in a few remote cities in Poland, and the alleged plans were never recorded even in a single word in the many years of notes of the Fuhrer's personal secretary, and the alleged methods of killing were spit out the first time (not in the much bigger initial war trials that filled 22+ volumes but now available and keyword-searchable on Yale Law School's website) from the mouth of a prison officer whose wife and children were kept captive, and the methods were never formally forensically proven and testified like in any other court murder cases (I challenged a few history PhD friends to find the court case numbers where the methods were testified with forensic examinations results, none of them could add anything leading to some archive numbers, and they love to use the "oral history" method). Of course it must be true because it is the official history anyways.
There's no need to infuse more self-hatred into the Germans. There are 2+ years of mandatory education for every children here in Germany to learn how bad and shameful their Grandparents generations were. And the Hollywood has been repeatedly using this historical theme to bombard the German identity and self-recognition to remind the Germans how bad they were according to the official story, and usually these Hollywood stories won Oscars.
How about a movie with people playing Bush and Blair as the villains and tell people what they have done? Just one of the many pieces of real history not emphasized in mainstream media but brought up by academic activists like Noam Chomsky.
No wonder such a movie will not be screened, only perhaps in some underground theaters the BRIC countries and its allies.
Okay... I actually try to keep the topic keyboard related, although I'm also distracted to wander in the off-topics a lot.
I posted 57 keyboards and you guys single out one joke out of 57 just to crusify me? Is it because of what I said in the Taihao thread and you want to spread the war zone over every thread posted by me? Well if you don't like my jokes you can just suck my Asian k.....keycaps... 
