哪些口语和俗语含有国家名称啊？

are you japanese?是骂人傻*的
开玩笑
He took French leave during the dinner party.
宴会上他不辞而别。

when you're in Rome,do in the Roman's way 入乡随俗。
（字面意思，当你在罗马的时候，要按着罗马的方式行事。）