10. France: A kiss on the cheek
This is a gesture made in the air or maybe lightly brushing someone's face, if you're particularly close. So for the Trump administration, remember: do not use tongue and do not leave a hickey.
9. Vietnam: Crossed Fingers
Given that most of the press corps is still waiting for Donald Trump and Sean Spicer to reveal that their fingers were crossed under the podium all along, this one should be a gimme. Trump has to avoid the cross at all costs.
8. Brazil: The O.K. gesture
In Brazil, the O.K. gesture is, again, roughly the equivalent of flipping someone off, but with somewhat more specific and scatological connotations.
7. Greece: The 'stop' sign
Called the moutza, this references rubbing ashes or offal in someone's face like you would once have done to a criminal. It's a pretty nasty gesture, and we can most likely expect it from Trump the next time he speaks to a Greek woman. He better watch out for this one.
6. Japan: Taking a business card without gravitas
It's considered polite to receive someone's business card with appropriate gravity. Take the card with both hands, consider it well, then tuck it away safely. To do otherwise communicates a similar dismissiveness towards the other person's career.
5. Saudi Arabia: Showing you feet
Ordinarily not a problem, for Westerners this can create a big issue because of one common physical tic: we often cross our legs when sitting.
4. Korea: Shaking with one hand
A two-handed, serious approach is considered polite. The one-handed, quick handshake that most of us do as a casual greeting is considered dismissive. It's what a superior does, and a rather impolite one at that.
3. Australia: The V-for-victory sign
This is surprisingly important, because in Australia, Britain and other Anglophone countries, reversing your hand (showing two fingers, palm inward) basically translates to "up yours."
2. Thailand: Thumbs up
Without getting into detail, suffice to say that Trump could tick Bangkok off his list with nothing more than a drive-by. He could probably kick off his first war by giving a thumbs up to the king. He must avoid at all costs.
1. India: The left hand
As a rule you don't eat or pass food with your left hand, because historically that's what people used to clean themselves after the toilet. As a concept, this bears no further explanation, save to recommend that readers use their imagination.