But in some countries, you'd be wrong: In Japan, for example, it's considered extremely rude to blow your nose in public. Instead, people will just sit for hours and sniffle away. All those Japanese Zen gardens and meditation techniques that you assumed were for attaining enlightenment? They actually grant people the inner peace to put up with the constant sniffing.

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Seriously, what do you think the green parts represent?

Similar nose-blowing taboos exist in Korea. And when you think about it, this attitude isn't all that weird. If you're sitting on public transportation after an unwise visit to the taco stand outside the adult bookstore, nobody's going to toss you an adult diaper and say, "Dude, just get rid of it already," no matter what loud, unpleasant growling noises your stomach might be making. And that's what blowing your nose seems like to most people in these countries. You're ejecting a mass of gross, disease-ridden bodily fluids into a bit of paper and then putting that bit of paper back into your pocket. Frankly, I'm not surprised that the Japanese make fun of us with racist party gags.

Debito Arudou
"The Gaijin Nose: Soon with exploding snot!"

But gift giving is one of those areas that American visitors overseas tear through like a herd of fanny-pack-wearing buffalo, leaving baffled foreigners and torn wrapping paper in their wake. In China, it's usually rude to accept a gift unless it's been offered to you three times -- anything less than that, and the gift offerer was just being polite and didn't really want to give you that panda. For Iranians, the "three times or I don't mean it" rule extends not only to gifts, but also to things like invitations to people's houses, which has almost certainly led to a lot of awkward dinner parties, movie nights, and marriages.

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God help you if you down some bad hummus and need to use someone's restroom.

In India, China, and most other parts of Asia, it's also considered impolite to open a gift in front of the person who gave it to you. I'm pretty sure this doesn't apply to gifts among family members, otherwise these countries must be home to the most depressing birthday mornings ever. But at other times the "unwrap in private" rule makes perfect sense. It demonstrates to everyone involved that the important thing is the giving, not what's inside the package. Also, if you open gifts alone, you're always able to hide the brief despair in your eyes as you see the ill-fitting sweater or Christmas ska album that your closest friend chose for you and realize that you are utterly alone forever and no one will ever, ever understand you.

This problem is so common that it's been given a sciencey-sounding name: proxemics. See, the distance between two people when they're talking to each other is not universal: In some regions (like Latin America and the Mediterranean), people tend to stand closer to each other than North Americans do, while in others (like Scandinavia), they leave more space. The problem is that this kind of space-decision is entirely unconscious, so that rather than thinking to ourselves, "Oh, he's standing too far away. I will accommodate his cultural needs," we think, "This person seems standoffish and I don't know why. Probably because he's a jerk. Look at his stupid jerk face."

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"If he doesn't come over here, I'm going to start waving with fewer fingers."

And that's the better scenario. Often, when faced with unfamiliar proxemics, we'll simply edge forward or backward, unconsciously trying to enforce our own culture's personal space. So the next time you're talking to a person in another country and the conversation ends with them suddenly tumbling off a cliff, you will know why.

Believe it or not, the U.S. is pretty much the only country in the West where this is a thing:

Jonathan Hyman
Did they actually remove a window for that?

In most of America, displaying your country's flag can mean anything from "I am proud of my country" to "I think colors are pretty" to "I never learned how to read, does this say 'I am nice' in Wingdings?" Much like ankle tattoos and Che Guevera T-shirts, flags are so ubiquitous that they simply don't make a statement anymore. In other countries, however, flying the country's flag is often associated with particular political views or parties: For example, a quarter of English people actually believe that displaying the English flag is racist.

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You should hear the s**t it talks about the French flag after a couple of pints.

The same thing goes for patriotism in general. It's not that everyone else in the world hates their own country and wishes they were American. It's just not expressed in the same way. Take this video, in which interviewers ask random Germans whether they're "proud to be German." Almost to a man, the Germans respond to the question in mild confusion. They're happy to be German, but they don't see the logic of being proud of something that's a complete fluke of birth location. To most non-Americans, saying "I'm proud to be American" is like saying "I'm proud that my parents have money" or "I'm proud of being born with only two nipples." It makes it look like you don't know the difference between personal achievement and sheer dumb luck.

But a lot of immigrants to English-speaking countries find this kind of universal small talk extremely difficult to adapt to, and not just because they have to stumble through phrases like "Please to be knowing not so good about these 'New York Giants.' Are dangerous?" It's not that people from other countries never open up to each other; it's that small talk and personal conversations are kept within certain social classes and situations. Interaction with your boss is formal and limited to work-related essentials. People don't ask you "How's your day going?" unless they're actually prepared for an honest answer. For these immigrants, having American strangers ask about their job or hobbies is a bit like the queen of England sitting down across from you in Applebee's and bitching to you about her corgis.

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Sir Piddlesworth can be such a little s**t.

The reverse applies when native English speakers are traveling overseas. We'll blunder our way into conversations, cheerfully asking strangers, street sweepers, and state dignitaries things like "What do you do for a living?" or "Wow, that's a big dead rat you're sweeping up. Do you have rats that big in your house?" When they don't answer with effusive extroversion, we're shocked at how unfriendly these foreigners are, not realizing that we're coming across like the kid at the party who just loudly asked about the thing growing on that lady's neck.