I'm not sure what you've encountered, but I meant that Germans don't care, and wearing traditional dress to a party is not going to shock them much. If anything

I'm not sure what you've encountered, but I meant that Germans don't care, and wearing traditional dress to a party is not going to shock them much. If anything, it may provoke them to join the party. Therefore, there's nothing inherent about negative reactions from a person of an in-group when someone from the out-group is trying out some of their customs.