Rude gestures and how to sneeze: A guide to being polite abroad

Say cheers or cheese, and if you sneeze – do it twice

Sit on this: The thumbs up is considered rude in Sardinia

Gestures should be used carefully when abroad for fear of misunderstanding. The cheery thumbs-up used by the English and Americans means "Sit on this!'" in Sardinia. In France, pressing a thumb against the fingertips means something is ooh-la-la parfait or just right.

In some countries, the V-sign can be negative, in others positive; in Italy, reversed, it approximates to "to hell with you". In some countries, flicking your thumb across the teeth tells the other person he's a cheapskate. Just about everywhere, grabbing the crook of your elbow and raising your fist is rude.

Equally rude, and definitely a breach of etiquette, would be not to respond to the widespread custom of toasting. The general theme of the common brief toast is "good luck" or "good health". Na zdravje (Slovenian), salud (Spanish), saude (Brazilian Portuguese), kia ora (Maori), egeszsegedre (Hungarian) and gezondheid (Flemish). The Ukrainians take this to the next level with budmo, meaning "Let us live forever!"

The Scandinavian drinking toast, skal (pronounced "skoal"), has a much more macabre background; as it originally meant "skull." The word is alleged to have come down from a custom practised by the warlike Vikings who used the dried-out skulls of their enemies as drinking mugs.

Photographers bring the best out of us by making us say "cheese". The old Czech phrase was pozor, vyleti ptacek, which literally means "Watch out, a bird will be released/fly out [from the camera]". In Serbia, they are asked to say ptica (bird). The Danish favourite is Sig appelsin (say orange).

Less sociable is the act of sneezing. In Japan one sneeze signifies praise (ichi home); two sneezes, criticism (ni-kusashi); three sneezes, disparagement (san-kenashi).

As for how to respond, in Mexico, one sneeze is answered with the word salud (health); two sneezes with dinero (money); three sneezes with amor (love); four or more sneezes with alergías (allergies).

In Iran, after the first sneeze you are supposed to stop whatever you were doing for a few minutes before carrying on. If the sneeze interrupts a decision, it is taken as an indication not to go ahead, and ignoring a single sneeze risks bad luck. However, a second sneeze clears the slate: you can do whatever you like after that.

Adam Jacot de Boinod is the author of The Meaning of Tingo and Other Extraordinary Words from Around the World, published by Penguin Books, and creator of the iPhone App Tingo, a quiz about unusual words.