I spent most of 2016 in Asia, mainly in Japan and Hong Kong. Even though I'm Asian, most people were able to tag me as a foreigner before I'd even uttered a word. Perplexed, I asked my friend, a local, why. "Well," she told me, "it's because of your body language. You're very American."
Very American, that is.
I was taken aback, but after applying some thought and a beer, I conceded we do have a number of gestures and postures that mark us as travelers. Many are universal and harmless. Others can make you look uncultured at best, or like a full-blown jackass at worst. So pay attention to these body language faux pas. You might just avoid unintentionally telling someone "up yours" in another country.