'Karen' does not smell like teen spirit

Smells like teen spirit? Not if you're an alternative music-loving green radical named Karen.

Twitter users are poking fun at a federal government brochure intended to teach students how to recognise signs of extremism.

Karen the environmental soldier starts off as a loving daughter lured into the alternative music scene and left-wing activism as a university student.

Her troubles with the law begin when she drops out of studies to live in a forest camp.

Social media's initial bemusement at Karen's case quickly turned into ridicule as the hashtag #freekaren began trending on Friday.

Not surprisingly, the Australian Greens were some of the most vocal in support of Karen.

"Karen sounds just the kind of student I'd take on for work experience," Tasmanian senator Nick McKim tweeted.

Others compared the affair to the bungled visa-crackdown Border Force operation canned following social media criticism.

"BREAKING: Border force apprehend man with radical leaf blower," said one user.

Others just wanted advice on signs of extremism to look out for.

"I've worked for Greenpeace, handed out Greens how-to-vote cards at polls and been to protests; have I been radicalised?" a user tweeted.

"#HeyASIO I saw a child wearing peace-sign earrings. She also told me she loves visiting the GBR. Should I make a citizens (sic) arrest?" another quipped.

Meanwhile, Justice Minister Michael Keenan is travelling to New York to attend a forum on countering violent extremism and Islamic State.

He's also due to meet young people with ideas to counter extremism.

Let's hope he doesn't run into any Karens.