They don't drink. They don't have casual sex. (And they're not necessarily religious).

Dion is a cocky, tanned, gym-junkie from Brisbane.

The 24-year-old is technically ‘famous’ for being one of the new housemates on Big Brother — but that’s not why we’re all talking about him today in the Mamamia office.

You see, what caught our attention was Dion’s proclamation on last night’s show that he’s “Straight Edge’.

Not “edgy” (don’t make that mistake) but Straight Edge.

Which, apparently, is a fancy way of saying he’s part of a movement that revels in being clean-cut.

“I don’t drink to relax,” Dion smugly proclaimed said on the show last night.

“I relax just by hanging out with friends and, you know, doing the same thing you would while drinking – but I just don’t necessarily need a drink to do it.”

He also won’t smoke, take drugs or engage in sex with anyone other than his long-term partner — so while most of the housemates will be partying/drinking/hooking up, Dion will be soberly watching on.

We’re intrigued.

Not because Dion’s making different (and admittedly, healthier) life decisions than the average 24-year-old; nothing too shocking there. But we’re fascinated by the fact this straight-180 behaviour has been rebranded as a cool, new social movement.

If you are too? Read on.

What even IS “Straight Edge?”

Straight Edge is a worldwide movement with hundreds of thousands of followers, although Urban Dictionary defines the term as a “philosophy/life-choice” involving abstinence from “activities that are a disgrace to their minds and bodies” —  such as lying, having sex in the abvsence of a true emotional bond, or drinking.

With principles like that, you might assume Straight Edge is some sort of born-again Youth Christian movement — but you’d be very, very wrong.

You see, Straight Edge apparently developed out of the US youth music scene in the 1980s, as a way for young people to rebel against the status quo. It’s sometimes even referred to as a subculture of hardcore punk, and a lot of its followers are into metal music.

Now it’s evolved into various subcultures, some of which are passionate about animal rights, and others who are fiercely vegan.

So: While most teens rebel by taking illicit substances and hooking up, straight edgers are SO hardcore they do the opposite. Essentially, they rebel by rebelling against the rebels.

(Anyone else’s brain hurt yet?)

How do I know who is straight edge?

Some followers of the Straight Edge movement have an ‘X’ symbol drawn or tattooed on their bodies.

Others announce it — on a reality TV show or otherwise — or embrace it quietly as a way of life.

There are even online forums where Straight Edgers can talk to other Straight Edgers about Straight Edge topics including veganism, sports and metal music.

Why would kids these days join?

We scoured Straight Edge forums for some personal stories, and found members’ reasons for joining ranged from teens looking for a way to justify their ‘clean’ lifestyles to their peers, to help with recovery from addiction.

“I struggle with a lot of peer pressure during my adolescents year in junior high… one day there was this kinda tragic story of how one of my friend ended up his life because of OD. From that moment, my conviction in straight edge became stronger and I decided to pledge my allegiance,” one said.

Another wrote,  “I was a junkie and almost everybody I knew did drugs and was in the drug business. When I moved [to Spain] I couldn’t find a dealer and decided it was the time to go clean for good”.

Others are, well, preachier:  “Basically, I just don’t find any appeal in using substances. I’d rather get “high” from going to concerts and enjoying my life in other ways then doing drugs and alcohol,” one forum user wrote.

“I can honestly say the idea of becoming so intoxicated you sleep with random guys and end up with an STD and vomiting all over yourself isn’t what I call ‘fun’,” one post said.

(Just FYI: you might think Dion sounds preachy, but he  told Channel 9 in an interview he’s not arrogant, just “over-confident a lot of the time”.)

So there you go.

Next time you’re offered an unwanted cigarette or mocked for not enjoying a beer at the pub, just look your friends up and down and say you’re considering going Straight Edge.

Just brace yourself for a bunch of questions.

Here’s some Straight Edgers being Straight Edge: