Anywhere in east Asia, never stick your chopsticks upright into a rice bowl. Apparently this is done for the dead and is considered very bad luck.

In the Arab world, never ramble on and on about how much you like anything that’s in your host’s possession, or they will be obliged to offer it to you. You will doubly offend if you take it. Note: this may also be true of elderly Jews, as seen in the Seinfeld episode “The Pen”.

In China, when dining with a business host on their tab, never finish all of your food. It would suggest that you have not been adequately fed and provide some embarrassment for everyone involved.

In Thailand and in other devout Buddhist countries, it’s considered very rude to show the soles of your feet to another person, or to an image of the Buddha. Bare feet are apparently a sign of disrespect.

In West Africa, the top of the head is considered sacred and it’s a tremendous affront to touch it. This is especially true for a child.

In South and Southeast Asia, it’s perfectly normal for straight men to walk around hand-in-hand and it’s a sign of friendly affection as usual as a slap on the back. In any Anglo culture, you’d pretty much have to want people to think you’re gay.

In most of Asia, never eat or offer or receive anything with your left hand. Prior to the advent of the modern, Western throne toilet and double-ply cotton toilet paper, the left hand was used for wiping your butt. Apparently enough people still do that that it’s considered pretty gross. Somehow, offering an object with both hands is perfectly acceptable.

Never point out to Greek people that their cucumber-yogurt-dill mix called Tzatziki is pretty much the same thing as Turkish Jajik. They will assure you that it is not, and that the Turks stole the dish and use inferior yogurt.

And finally, on the topic of food-as-politics, be wary of describing falafel as an Israeli food to an Arab. Falafel is in fact Israel’s national snack (having thankfully replaced Wiener Schnitzel back in the 1980s), but the PLO was so angry when the Knesset declared that fact that the protested at the United Nations.