Lived in several countries and am chuckling at many of these. The first few weeks somewhere can be baffling!
I'm the UK, it took me a long time to understand the goodbye carry on, that is, when someone says they're going, they don't actually leave. They say it at least 3 x before getting up and going.
And that when you ask directions, it's like - up the road to WHSmith, left then when you see the station, look up and you'll see a tall chimneypot - the white building to the left is the shop you're after"
as opposed to, first left then 3-4mins walk to number 72.
I never understood the tea round thing either. I once worked a week at a place where they did tea rounds approximately every hour. As I didn't drink tea and because I was new and no one spoke to me, I didn't partake. On the Friday, a guy plunked the tray on my desk with 9 cups and said, "About time you did the tea" so off I went to the kitchen (which I'd never used) with cups for people who didn't speak to me, to make orders that I couldn't remember.
I couldn't quite believe their pettiness and decided it was not a work environment I wanted to stay in.
In the States I'm always freshly surprised by how formal greetings can be - yes Ma'am etc, and "Welcome to the United States of America!" even from the grade school teacher 