I worked with some Russians a few years ago. Great guys. One wasn't very well adapted to American culture. He came to my cube one day. He's like "Let's go get a smoke", but his face and tone was flat, so it came across as "You've pissed me off in some way and I'm probably going to kick your ass now". I demurred. A couple more offers over the next few days and I finally relented (I don't smoke, but went to hang out). Pretty soon he was smiling and cracking jokes. A few months later he asked me, "Why do Americans always have to act happy? It's so fake."
*edit: I a word