Tourists who don't do their research can make all kinds of cultural gaffes abroad - or even run into trouble with the law - for something as simple as a hand gesture or a drink order.
While some no-nos are a no-brainer, holidaymakers can offend locals even by doing something that is perfectly acceptable at home.
In a new thread, Reddit users have revealed some of the worst mistakes made by holidaymakers in their hometown or country.
Don't give this hand gesture in Britain
The V sign, where the index and middle finger are parted, can mean peace, victory or even the number two in American Sign Language.
But in Britain, Ireland, Australia and New Zealand, it is an insult if the palm of the hand faces the signer.
A Reddit user wrote: "It's considered the same as giving someone the middle finger. But most people I know realise that when a non-Brit does it, it's not a case of being rude, just a case of not realising."
The peace sign, where the palm faces away from the signer, is perfectly acceptable. Americans and Canadians, for example, often make the gaffe when they show the V sign for the number two.
Don't touch people's heads in Thailand
Thailand is one of Asia's most popular destinations, but visitors should be careful not to get too friendly with the locals.
A user offered this warning: "Don't touch people on their heads, it is the highest point of the body so therefore it's the most respectful part."
Pointing your feet at a Buddha statue is considered very rude and visitors risk being thrown in jail if they disrespect Thai King Bhumibol Adulyadej.
The Redditor added: "If you step on money, you'll be thrown in jail. It has the king's face on it and disrespecting him in any way (like stepping on his image or saying you hate him) will get you a one-way ticket to a not very nice prison."
Don't antagonise the Queen's guards in Britain
Soldiers from the Queen's Guard are a popular attraction for tourists at Buckingham Palace and Whitehall, but they're not props for photos.
Reddit users were warned not to antagonise the soldiers in full dress uniform (red tunics and bearskin hats).
A user wrote: "They're not decoration, they're serving soldiers. Have a good gawp but leave them be."
Another Redditor added: "I can kind of get it, though. They're never portrayed seriously in movies or TV shows."
Don't use the 'OK' sign in Brazil
A Reddit user from Brazil explained why visitors shouldn't make the 'OK' gesture with their fingers to Brazilians.
They wrote: 'The "OK" thing Americans do with their hands means "Shove it up you're a**". So don't do it.'
Don't order this drink in Northern Ireland or Ireland
In bars in North America, the 'Irish car bomb' - a shot of Irish cream and whisky dropped into a glass of Guinness - is a popular frat boy cocktail.
But, due to the Troubles, it's an offensive name in Northern Ireland and Ireland.
The same goes for the black and tan - and mix of dark and pale beer.
It was a nickname given to the Royal Irish Constabulary Reserve Force, which became notorious for a brutal crackdown during the Irish War of Independence.
Instead, ask for a "half and half".
Don't show the bottom of your feet in the Middle East
In the Middle East, it's an insult to show the soles of your feet or shoes.
A user wrote: "When I lived in the Middle East, showing the bottom of your feet (like when your legs are crossed) was offensive, saw expats do it all the time though."
Another user added: "Which ties into how throwing your shoes at someone is such an insult in the Middle East. The foot is the "lowest" part of your body, and you're throwing something that spends most of its time touching your feet."
Don't wear your shoes in someone's house in the US, Canada or Sweden
Although it is perfectly acceptable in some cultures, this applies as a general rule in countries such as Canada, the US and Sweden.
A Redditor wrote: "In the US, look down when you enter a house. If there are shoes near the door then assume it's a shoes-free house. Many houses are shoe-free, it saves so much cleaning hassle."
Another user added: "Sam in Sweden. Why would you drag that filth from outside in to your home?"
- Daily Mail