Parties must be very different in Switzerland, at least according to DillSe.
"Met some Swiss guys at a house party after a mutual friend's wedding. They couldn't believe that we were all actually drinking out of red Solo cups, it blew their minds. They kept on taking pictures and saying 'It's just like the movies!'"
If you think smiling is the universal sign of friendliness, Spectrum2081 has news for you.
"As someone born in Europe but very much an American, it took me a while to get accustomed to it and I was reminded of this when traveling out of states.
Americans smile a lot when talking. To Americans, it signals that you are warm and friendly, seeking to encourage a conversation. To a European, it's rather strange and a bit disconcerting to be talking to a stranger who is smiling for no apparent reason. It signals that you are superficial and disingenuous, like you're trying to sell something... or possibly mad/dangerous."
Speaking of unfriendly, Julius_OU points out another mode of communication that's not as acceptable outside of America.
"In many African countries/cultures, looking at someone dead in the eye when talking to them, particularly adults, is very very rude. In Murica, looking an adult in the eye is a sign of respect/confidence in the speaker."