Boys and girls across Ireland from all social classes are being pressured into full sexual intercourse and other acts to "feel like they are part of a gang".
Dr Niall Muldoon, clinical director of the Cari Foundation, which counsels children who have suffered sexual abuse, told the Herald that "initiations" have become more widespread over the past decade.
He believes that the internet is in great part responsible for this increased sexualisation of young people.
"We talk about television and the way it affects young people's behaviour -- programmes like [Channel 4 series] Skins -- but what children see through their mobile phones or on the net, is far worse," he insisted.
"In the past, if you didn't know what something was, you'd look it up in a dictionary, you'd ask someone. Now you Google it, and immediately, images and videos show up and they include very graphic detail. There is no way for teenagers to avoid it and it normalises situations that are not ordinary.
"About 10 years ago we started becoming aware of 'initiations' where young teenagers were being pressured by a group of 'friends' into sexual acts.
"They used to happen in areas [of the country] that were dangerous, and more violent than average, but now, it's developing into less dangerous areas and it's happening from a much younger age.
"We're aware of cases of 12- to 14-year-olds who are being pressured into sex -- full intercourse, oral sex, and anal sex.
"At that age, you're not mature enough to deal with the repercussions of these acts, it doesn't make sense.
"Every so often someone will come forward and say that it was rape, and obviously it's very difficult to assess.
"And the problem in dealing with this type of situation is the issue of consent.
"Both parties could be saying that it was consensual but legally, it should never have happened.
"There is no way of confirming who said or did what, especially if a whole gang turns against the person who said it.
"There is a code of silence and it's very difficult for parents to know what's going on."
Dublin-based consultant psychologist Owen Connolly lectures in childcare and parenting and he is adamant that while teenagers may feel like they are choosing to take part in certain sex games out of their own free will, it is never truly the case.
"Young people aged 13- to 15-years-old do not have free will as such, they're governed by fear -- fear of what people are going to think of them," Dr Connolly told the Herald.
"So the opportunities for them to make a choice are very limited.
"Thirteen- to 19-year-olds are in a very vulnerable position, it's a narcissistic age when their consciousness of themselves is very elevated, and others can take advantage of that.
"We've had cases of young ladies and their friends being coerced into meeting with boys they'd met on Facebook and being pushed into having sex at a particular place.
"One of them had a breakdown as a result of it.
"Children and young people only believe that sex is penetrative sex, they don't recognise oral sex as a sexual act.
"They don't think it's a big deal and they're make to believe that everyone is doing it. It's dreadful."
The Sexual Violence Centre in Cork is one of various agencies which have to deal with the repercussions of such initiations or 'games'.
The centre's director Mary Crilly has admitted that she is extremely concerned by the increase in cases of violence against teenagers committed by other teenagers.
"Most of the teenagers in the sexual violence centre were [sexually assaulted] by other teenagers," she said. "A lot of them didn't really know what was happening, they didn't want to do it but neither did they want to be isolated from their peers.
"They wouldn't be part of the gang if they didn't, so they do and it gets out of hand."
In the long-run the consequences of taking part in a initiation can be devastating, Dr Muldoon explained.
"Any individual taking part in a group initiation is placed in a situation of blackmail where they feel they cannot talk about it.
"The more they remain silent, the more they will feel ashamed and when they become adults, this can lead to self-harm or addiction."