Don't Mention the War

So I'm living with an italian and a german. So, what rule applies to an american in this situation? In the words of John Cleese: Don't mention the war.
It turns out, I didn't have to. The italian did it first. That's right. Marcos brought it right out in the open and Ulrich kind of stared at him and I left the apartment for two days. I'm going back now. I wonder what I'll find...