Around a woman who is pregnant, do not mention the pregnancy or congratulate her on her pregnancy. I am told (by a German) that unlike in American culture, Germans do not make a big deal of pregnancy itself, such as by having baby showers, etc., as we do in the States. If I heard her correctly, it is almost considered rude to draw attention to the pregnancy or to give baby-related gifts or cards before the birth. Others can correct me if I am wrong but I am just reporting what a German told me.
Also, I am told that Germans consider it rude -- quite unlike in the States -- for one to have one's free hand (i.e. the hand not holding the fork) underneath the table as one eats. Germans keep both hands visible and above the table as they eat, is what I have been told. Again, others can correct me if this is wrong.
Another point: Often, in the States (or at least in the South), when we say "hey, how ya doing?", it is meant as no more than a hello. We don't need or expect a full answer or even a short one. But ask a German this question, and expect an answer. This is most true perhaps when using their native greeting "Wie geht's?" (literally, "how goes it?") Germans will tell you how it is going. They will look at you perplexed if you quickly walk by them saying "Wie geht's?" and walk off before hearing their reply (perhaps congratulating yourself for having given that German a nice hello). In short, if you mean simply, "hello," then just say, "hello" or, in German, "Hallo."" (Paul Le,
I can't explain it but I completely relate to all of these. As I say often, America is largely a Germanic country and maybe it influenced me. And maybe you too.