[Michael81Dus]

So, did I get that right? Foreigners may make jokes about WWII (e.g. the lame joke about the Germans invading France march in shade), but Germans may not?

WWII was a fair war, at least for the military. (The bombings of civilians, mass-slaughtering of innocent people and expelling of people is not the military part of the war.)

Poland had the chance to defend itself, just as France and all the others had and in the last years, Germany too.

[LibWhacker]

Foreigners may make jokes about WWII (e.g. the lame joke about the Germans invading France march in shade), but Germans may not?

Of course not! If I had been a follower of Charles Manson, wouldn't you say it'd be a bit tacky for me to joke about Sharon Tate?

[Lazamataz]

So, did I get that right? Foreigners may make jokes about WWII (e.g. the lame joke about the Germans invading France march in shade), but Germans may not?

Correct. The perpetrator of a crime should not joke about the crime. You never mention a rope if you've been the leader of a lynching.

Where may I send the invoice for your very first lesson in Human Etiquette?

[Lazamataz]

Also:

WWII was a fair war, at least for the military. (The bombings of civilians, mass-slaughtering of innocent people and expelling of people is not the military part of the war.)

Yet, those decisions were made by your top military leader of the time. Furthermore, those decisions were manifested using military personnel.

No, the bombing of civilians, mass-slaughtering of innocent people, and the expelling of people were all 100% military actions. Unfortunately, you may not compartmentalize like that in order to appease your collective conscious.