When one curls his thumb and index finger into a circle and points the other three fingers upward, one’s intention is to tell the other party that everything had been “OK”. That works fine at home in the US, but in other countries including Malta it’s considered vulgar.

The OK sign is not OK in many places, including most of the rest of Latin America, plus Germany, Malta, Tunisia, Greece, Turkey, Russia and the Middle East, William Ecenbarger wrote in The Los Angeles Times.

He wrote: “In Sydney, Australia, I simply hailed a taxi, opened the door and jumped in the back seat. The driver narrowed his eyes. ‘Where to, mate?’ he asked in a voice that could chill a refrigerator.

“In Marrakech, Morocco, I crossed my legs during an interview with a government official. Immediately, a hush fell over the room.

“In a restaurant in Mumbai, all I did was reach for a naan. A diner at the next table shot me a look that stuck two inches out my back.

“It took years before I realised what I’d done.

“It turns out that in each case I had, unwittingly, committed a faux pas. To varying degrees, I had offended my hosts. My only comfort is my ignorance. I take solace in Oscar Wilde’s observation that a gentleman is someone who never gives offence – intentionally.

“And after nearly 25 years of travel on six continents, I have learned the hard way that getting through Customs is a lot more difficult than just filling out a declaration form. It means navigating a series of cultural booby traps. It means understanding that although people everywhere are the same biologically, they can be worlds apart in their habits and traditions.”