Avoiding so many of the long standing dark humour Brit/German exchanges : e.g. " Remember ,next time its your turn to have the Italians"
Some "actuals" come to mind:
"Sir, So were you actually shot down when flying in the Luftwaffe?"
'"Oh yes, three times; Once by the enemy"
"So your father was one of the last to be flown out of Stalingrad then?"
" Did he claim his Air Miles? "
And from a Dane who had ,shall we say , certain right wing leanings, upon being criticized:
" I'll have you know that I had an uncle who died in a Nazi concentration camp "
"He got p*ssed and fell out of a guard tower"