Same solution applies, really. Make them go through what they did to East Germans during "reunification".
Note: this is a joke, no one should have their residence taken away like that. If it had happened to people like this, though, it may have taught them some perspective and empathy.
"spent some time in East Germany when it was East Germany" usually means they're West Germans who used to visit relatives in the DDR.
Same solution applies, really. Make them go through what they did to East Germans during "reunification".
Note: this is a joke, no one should have their residence taken away like that. If it had happened to people like this, though, it may have taught them some perspective and empathy.