Kaf Okpattah can speak the language of scammers. “Squares is one word which comes up a lot. That’s bank cards,” he says. “Fullz … that’s a person’s full financial information.”

In his new book, Scam Nation, he goes through more. “Clicking”, which means using stolen details to commit online crime; “addy”, which is used for the shipping address for fraudulently bought gear; and “mule herder”, meaning someone who recruits and manages people accepting stolen funds. Many of these are words he learned at school, he says.

Okpattah describes contemporaries using stolen “fullz” to buy designer trainers, getting the details from the dark web and having their spoils sent to unrelated “addys”. They seemed to discuss it casually, only thinly disguising what they were up to from their teachers.

“Fraud was part of my life, just by the nature of when I grew up, who I grew up with and where I grew up,” he says when we meet to talk about the book. “All of my friends were doing it and discussing it and DMing each other about it. So it was just part and parcel of normal life.”

Now in his 20s and an investigative journalist at ITN, in Scam Nation he looks back on his experiences and how close he was to falling into the world of fraud, then describes moving into news journalism and trying to track down and expose criminals.

The scammers he uncovers are typically young, and the internet and social media play an important role – they are used by fraudsters to facilitate their crimes and show off the spoils. One scammer, whom he describes as “basically the Kim Kardashian of fraud”, whizzes around on an electric scooter and tells 150,000 social media followers about his latest con.

The lure of what might look like free money – and possibly feel like a victimless crime if you think banks will reimburse everyone – is strong for those who do not have much, which is why students are often drawn in, he suggests. One chapter focuses on a university student who has been approached by someone trying to recruit her as a money mule, offering cash in exchange for the use of her bank account.

Okpattah says some of the recruiters are students themselves. “Sometimes they’re not students, but most of the time, I’d say in every university year group, there are about 50 fraud boys,” he says. “They’re students themselves, they’ve grown up doing this thing and they’ve stayed in this world.” People higher up the chain are telling them to get hold of account details for them to use to transfer cash into and, he says, they think: “I’m not going to go far – I’m going to go to that person in my economics class or my philosophy class.”

Some of the people he highlights in the book seem to be motivated by the chance to show off rather than any real desire for the items. Is that right? He says yes – if your parents “can afford [to buy] you the nice things and you live that comfortable life and you’ve never had to see your parents worrying about rents, bills, etc, etc, then it’s more of ‘check me out, I’m being cool.’”

With the code words and influencers, it feels like a parallel of the manosphere and, as the parent of a teenager, I ask if there are any words I should be alert to.

“I wouldn’t be that concerned if my son was saying ‘squares’ because it might just be him talking about bank cards. And probably by the time he’s 13, he’ll probably have a bank card,” he says. “Fullz, on the other hand, that’s a person’s full financial information. Why on earth would a 13-year-old be discussing full financial information unless you’re: a) planning on handing yours over; or b) planning on taking someone else’s?”

“Deets”, too, he says. Although this is mostly used with no criminal connotations, in the world of fraud it can be synonymous with fullz. “So those are the two things,” he says. “If you see your children searching those terms on social media platforms in their recent searches, then that’s a cause for concern.”

He adds: “If the algorithm is showing people with flashy items holding lots of cash, then the chances are that they are either in that world or being sucked into that world … What teenager doesn’t want flashy things? And I’d try to nip that in the bud as quickly as possible. Probably take their phone and chuck it into the Thames.”