Watch out for "happy slapping," the latest youth craze to sweep Britain.

It's not a new dance step or even a new designer drug. It's a criminal assault.

Groups of teenagers approach an unsuspecting person and begin punching and kicking him or her while capturing it all on their mobile phone cameras. The images are later uploaded and shared on the Internet.

The victims can be young or old, male or female. Bus stops, subway stations and parks are considered prime venues. In most cases, the injuries are minor. But last month a 16-year-old girl from Manchester was knocked out and spent two days in hospital with head injuries.

The craze apparently started in London late last year, and has since spread across the country. British Transport Police said they had investigated about 200 incidents in London alone since the beginning of the year but acknowledged that most assaults go unreported.

Happy slapping is the latest manifestation of what Britons call "yob culture." The word "yob" dates back to the 19th century; it may derive from "boy" spelled backward, and it denotes loutish, anti-social behavior associated with working-class youth in Britain's urban centers. The British soccer hooligan is the quintessential yob.

On a popular yob blog, a person identified as "Huni bo" from Sleaford said: "I happy slap people. I dnt see nowt wrong wit it tho, ima good person! Its well funni tho!!"

"It's not funny," replied "Spartanette" from Swansea. "If it's just among mates and you actually know the person, then it's harmless, but when you do it to someone you don't even know, you deserve a beating."

"So I deserve a beatin yeh?" replied Huni bo. "Wes onli do it ppl lyk are age ish, say from 15-19 or 20. summats, wunt do it to an old man, even though they keep avin a go at us, an it dus are heds in!"

Violent, anti-social behavior is hardly news in Britain. It was common in Charles Dickens's time and was made iconic by the 1971 Stanley Kubrick film and earlier Anthony Burgess novel, "A Clockwork Orange." But a particularly vicious incident last month once again focused national attention on the problem.

Phil Carroll, 49, a father of four from Salford, a modest, middle-class suburb of Manchester, confronted three youths from a nearby housing project after they threw a stone at his car. Suddenly, he was set upon by a larger group, who left him bleeding and unconscious in the street. He was in a coma for two weeks.

But it wasn't the attack that drew headlines. It was Manchester police Chief Supt. David Baines's graphic characterization of the attackers:

"They are gangs of feral youths who are under no control from adults, parents or anyone else," he said. "They are not concerned about respect or their responsibilities. The criminal justice system holds no fear for them. This is a national problem. Today it is Salford. Tomorrow, it will be somewhere else."

A week later, Prime Minister Tony Blair pledged to create "a culture of respect" in Britain. He used the annual queen's speech, in which the government sets out its legislative agenda for the year, to declare war on yob culture.

"It's time to reclaim the streets for the decent majority," Blair told Parliament. "People are rightly fed up with street corner and shopping center thugs . . . [and] binge drinking that makes our town centers no-go areas for respectable citizens."

One new tactic that will be tried this summer is the establishment of "dispersal zones," designated areas in cities where police have powers to impose curfews, ban groups of two or more youths from congregating and send youths under the age of 16 home to their parents. Those who defy the police risk large fines.

The government also floated the idea of forcing young offenders serving community service sentences to wear bright orange jumpsuits in order to shame them. Juvenile crime experts were doubtful, and the idea appears to have been scuttled.

"In my experience there is no benefit gained from humiliating offenders in public," said Rod Morgan, the government's chief adviser on juvenile crime.

The government's main weapon against yobbery is the ASBO. An acronym for "anti-social behavior order," it is a civil order obtained from a court that prohibits a person from engaging in certain narrowly defined activities that are not necessarily criminal but are clearly anti-social.

A neighbor who habitually throws loud drunken parties might be slapped with an ASBO that sharply curtails the number of guests allowed on the premises after 9 p.m. People who violate an ASBO may be jailed.

At first, the process of obtaining an ASBO was bureaucratic, slow and costly. Only 600 were issued in the first three years of the program, which began in 1998. But the process has been streamlined, and last year 2,600 ASBOs were issued.

Some community activists say the targeted use of ASBOs has been an effective crime-stopper, but others point to abuses.

In one well-publicized case earlier this year, a woman from Bath who had tried repeatedly to commit suicide was issued an ASBO that prohibits her from going near rivers, bridges, train lines and tall buildings. A woman in Scotland received an ASBO to stop her from answering her front door in her bra and panties.

The problem, according to civil libertarians, is that ASBOs allow people to be jailed for activities that are not crimes, such as using foul language or answering the door in one's underwear.

Children as young as 10 have received ASBOs. That prompted a warning earlier this month from Alvaro Gil-Robles, the Council of Europe's human rights commissioner. He said the government's policy was "criminalizing" children, and that no child under age 16 should be jailed for violating an ASBO.

Although crime rates in Britain have been dropping for a decade, the public perception is that crime and anti-social behavior are on the rise. There has been no shortage of tough talk from politicians.

In the run-up to last month's general elections, Michael Howard, leader of the opposition Conservative Party, vowed to "make yobs fear the police."

"I want policemen -- and women -- to have the confidence to eyeball these characters; to invade their personal body space, just like they are invading ours; to confront and challenge their unacceptable behavior," he said.

"I don't want members of the public looking over their shoulders; I want the yobs looking around in fear."

Morgan said a good start would be for politicians and the news media to stop describing children as yobs, and their anti-social behavior as "feral."

"They didn't choose their parents or their neighborhoods, and they can't walk away from their circumstances," he said. "I don't think these are appropriate words if we are trying to build a culture of respect."