Do you know the secret to good German baking? Jew concentrate
I don't understand how someone could say something like that
Haha! Come on. You know the answer.
There are people alive today who might have escaped from those concentration camps, or whose grandparents might have died there, so it is very hurtful to make light of the suffering that happened during World War II.  It is also offensive to people from Germany who had nothing to do with the Holocaust, because suggesting that the entire population benefited from it is simply not true.