Lived with two Germans this year and they were pretty sound, if at most, one needed a haircut.
Even though they were younger than me they hated WWII, it still is a sore point over there and it goes further than the fact they lost. Even halfway quite a large proportion disagreed with it and it seems even 3 generations later they carry a lot of shame. By all means banter but don't bring it up it's not really funny to them.
The football rivalry is a funny one which most fans understand. I support Arsenal and for years have seen Liverpool, Chelsea and Manchester UTD as my main rivals. Spurs, even though our 'traditional' rival, is more from their side than ours. Apparently the same applies with the England/Germany rivalry; they barely remember 1966. It's easy to forget when you win it twice afterwards, and get to another 3 finals. The best we've done since 1966 is the semis both in the Euros and the WC, both of which we were knocked out by guess who and by what method.