Schoolchildren are asking teachers how to strangle a partner during sex safely, a charity says, while official figures show an alarming rise in the crime related to domestic abuse cases.
Warning: This article contains references to strangulation, domestic abuse and distressing images.
It comes as a woman whose former partner almost strangled her to death in a rage has advised anyone in an abusive relationship to seek help and leave.
Bernie Ryan, chief executive of the Institute for Addressing Strangulation, has been running the charity since its inception in 2022 after non-fatal strangulation became a standalone offence.
"It's the ultimate form of control," she says.
She says perpetrators and victims are getting younger, while the reason is unclear, but strangulation has seeped into popular culture and social media.
"We hear lots of sex education providers, teachers saying that they're hearing it in schools.
"We know teachers have been asked, 'how do I teach somebody to strangle safely?'
"Our message is there is no safe way to strangle - the anatomy is the anatomy. Reduction in oxygen to the brain or blood flow will result in the same medical consequences, regardless of context."
A recent review by Conservative peer Baroness Gabby Bertin recommended banning "degrading, violent and misogynistic content" online.
Violent pornography showing women being choked during sex she found was "rife on mainstream platforms".
Ms Ryan says she "wants to make sure that young people don't have access to activities that demonstrate that this is normal behaviour".
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Strangulation is a violent act that is often committed in abusive relationships.
It is the second most common method used by men to kill women, the first is stabbing.
According to statistics shared by the Crown Prosecution Service, in 2024 there was an almost 50% rise in incidents of non-fatal strangulation and suffocation - compared to the year before.
Domestic abuse victim Kerry Allan has a message for anyone who is in an abusive relationship.
Kerry met Michael Cosgrove in September 2022. While she said "at the beginning it was really good", within months he became physically abusive.
In August last year her friends found his profile on a dating app.
"I confronted him and he denied it. I knew we were going to get into a big argument and I couldn't face it, so I said I was going to my mum's for a few days and take myself away from the situation.
"I came back a few days later and stupidly I agreed we could try again and everything escalated from that."
In the early hours of 25 August the pair had come in from a night out at a concert and got into an argument.
"He was having a go at me, accusing me of flirting with other people, and I was angry. I told him he had a nerve after what he'd done to me in the week and how he humiliated me.
"I told him that I wanted to leave, that we were done and that I wanted to go to my mum's and that's when it got bad.
"He pinned me to the bed and that's when he first strangled me."
Kerry says this was the first time she'd ever been violently assaulted. Cosgrove was eerily silent as he eventually let go and Kerry gasped for air.
"I remember trying to get my breath back, I was crying and hyperventilating... I was sick on the bedroom floor and I was asking him to go."
Cosgrove strangled her for a second time before letting go again.
"He was saying I wasn't getting out of this bedroom alive. I was dead tonight, he hoped that I knew that. Just kept saying how I'd ruined his life."
"I remember feeling a sort of shock thinking at this point, I'm not going to get out of this bedroom, he's actually going to kill me."
Kerry began screaming and shouting for help as loud as she could.
Her neighbours heard the commotion and called the police. While they were en route, Kerry was once again being assaulted.
"I ran over to the bedroom window and tried to jump out, he grabbed me as I went to open the window, and we struggled. And then I was back in the same position, he was on top of me on the bed, and his hands were round the throat again. But this time it didn't stop.
"I remember trying to struggle and trying to kick out and hit him and I just kept thinking that I definitely was going to die, because at this point, it wasn't stopping."
The next memory Kerry has is opening her eyes to see police and paramedics in the bedroom.
Cosgrove had heard the sirens, jumped out of the bedroom window and went to hide in Kerry's car.
Kerry remembers opening her eyes to paramedics caring for her: "I remember thinking, I'm alive. I couldn't believe it. I couldn't believe that I was alive and I wasn't dead. My last memory is him being on top of me with his hands on my throat."
She gives this advice to anyone who is in an abusive relationship: "Please speak to somebody, whether it's friends, family, a work colleague, whether it's somebody online, whether it's a charity that you're directed to, any sort of abuse is not okay.
"Whether it starts off emotional, they often start off that way, and they escalate, and they can escalate badly.
"Take what happened to me as a huge warning sign, because I wouldn't want anyone else to be in the position I've been in the last eight months."
Cosgrove was found guilty of attempting to murder Kerry and intentional strangulation.
He will be sentenced in July.
(c) Sky News 2025: School kids asking for advice on strangulation during sex - as abuse victim issues warning