In a memorable episode of Friends, Chandler is standing on an icy pavement outside the Central Perk cafe when Joey arrives to meet him. "Is Phoebe here with the cab yet?" Joey asks. It is a stupid question: there is no sign of Phoebe or a taxi. "Yeah," says Chandler.  "She brought the invisible cab. Hop in!"

This is a classic example of sarcasm, which has been defined as saying the opposite of what is true in order to make someone look or feel stupid.¹

Chandler has been nominated as the most sarcastic character on TV,² and his barbed remarks are a key part of the series' comedy. But in real life sarcasm can be extremely hurtful. The term in fact derives from a Greek verb meaning "to tear flesh".

Now the authorities in China are officially recognising its cruel side and taking steps to change people's behaviour.

The BeijingChina's capital. Government Service Administrative Bureau has issued a new set of rules for its employees. The aim is to improve its "service etiquette" and make them nicer to the people they deal with.

The rules forbid "tossing or throwing" paperwork at a member of the public, even if he or she has filled it in wrongly. They also include a list of banned phrases, such as "don't you understand Chinese?" and "there is a sign, read it".

Sarcasm is often said to be the lowest form of wit.³ But it also has many defenders. The saying is sometimes completed with the words - attributed to Oscar WildeAn Irish writer famous for his witty remarks and plays, such as The Importance of Being Earnest. - "but the highest form of intelligence."

Recent research⁴ has found that sarcasm can make people think more creatively and work together better. This is because the brain has to work harder to take in the difference between what is said and what is actually meant. Students in Israel listening to a phone company's helpline proved much better at dealing with sarcastic complaints than with ones that were just angry. 

The researchers add, however, that you should be careful about who you are talking to. Sarcasm is fine between people who get on with each other, like Chandler and Joey, but someone who does not like you or know you is likely to take it badly.

Writing in her blog, LK Greer concedes this point. But, she says, "sarcasm as a form of humour can be delightfully funny, illustrate the absurdity of human behaviour, and even be educational".

"Having a sassy sense of humour doesn't make a person bad," she adds. "Nor is a message delivered with sarcasm necessarily negative."

She gives the great satirist Tom LehrerAmerican satirist and musician, best known for his humorous songs of the 1950s and 1960s. as an example. In a song about America's pollution problem he sings: "The city streets are really quite a thrill - if the hoods don't get you, the monoxide will."

According to one psychologist, Dr Penny Pexman, sarcasm is a useful way of giving vent to our feelings when things go wrong. This is because it can encapsulateSummarise. both our expectations and our disappointment at the same time: for example, if rain spoils a picnic we might say, "We picked a fine day for this, didn't we?"

Yes: Making fun of people is incredibly hurtful, and it is the weakest who usually suffer most. Those who do it pick on their victims' most vulnerable points, and sarcasm is the most horrible form of it.

No: Mockery can be gentle, and as a form of humour between friends it is fine. It can be a very good thing when it is directed against those in power or those who take themselves too seriously.   

Or... Whether it is right or wrong, it is part of human nature, and no one can ever change that. If we are going to get along with other people, we have to be able to take a joke.