On Monday, executive councillor and former pro-democracy legislator Ronny Tong Ka-wah said he had seen a viral video of overseas teenagers stapling their bodies, prompting him to ask if Lam’s injuries had been inflicted by copycats.

An online check shows the painful practice is not only an act of self-harm performed by troubled individuals, but also a bizarre feat relished by extreme thrill-seekers.

Who are the teenagers stapling themselves?

International daredevils have been stapling themselves – and posting videos of the ordeal online – for almost a decade.

In the past few years, young men have been taking part in the 100 Staple Challenge, where a person is subjected to 100 staples on their body, either applied by themselves or by another person.

Another staple-related challenge is the Staple Gun Roulette, where a participant spins a wheel,which will indicate which body part he or she will be stapled on.

One staple gun roulette clip by UK-based YouTube channel WheresMyChallenge gained almost 3.5 million views.

A recent clip making the rounds is of American rapper Lil Uzi Vert, who unleashed a staple gun on his own head.

On a thread on social discussion site Reddit earlier this year, most in the online community were unimpressed by a person taking part in the 100 Staple Challenge.

“Who is stupid enough to do that,” one user questioned. “I remember when challenges weren’t just idiots trying to get famous,” another said.

Why are they doing it?

Frances Law Yik-wa, assistant professor of social work at the University of Hong Kong, said it was likely people who were stapling themselves were trying to validate their existence, and show others that they were unique and tough.

“They think this is a way to certify that they have some sort of value,” she said.

Law said young people who did so ought to be counselled to realise that they need not resort to such action to feel a sense of self-worth. She also cautioned that more publicity around the trend without a proper warning could risk encouraging others.

She had not heard of Hong Kong youth taking part in the competitive stapling videos.

Are people stapling themselves in Hong Kong?

According to Ivy Kong Siu-wai, supervisor of YMCA’s school social work department, she had not come across videos of Hongkongers stapling themselves.

But there have been cases of Hong Kong high school students stapling their limbs as a form of self harm – and it has been a common trend for some time, she said.

She was aware of three cases in the 10 schools that she works with, but said many people would hide their wounds or keep them a secret.

It was a common way for young people – particularly young women – to relieve their emotional stresses or get attention, Kong said.

YMCA is working on educational programmes for young people and helping them to find healthier ways to overcome their problems, she said.

Has there ever been a criminal case in Hong Kong involving torture by stapling?

Two veteran senior police officers, who have been involved in detective work for 20 to 30 years, said on condition of anonymity that they had not seen crime cases in which staples were used.

“Triads torture people by slicing off fingers or arms with a knife or beating up the person with a baseball bat. I have never seen a case where staples were used,” one officer said.

He said while it was obvious that stapling someone caused pain, he doubted if the act was extreme enough to be used as an instrument of torture.

The other officer said he heard of self-harm cases involving students, but the acts only involved one or two staples punched into their limbs.

WHERE TO GET HELP

● 24-hour hotline at Suicide Prevention Services: +852 2382 0000

● 24-hour hotline at Samaritan Befrienders Hong Kong: +852 2389 2222

● Society for the Promotion of Hospice Care: +852 2868 1211