Teenage gossip used to be scribbled in notes passed during class. Crude jokes were confined to the locker room.

Now snide comments, inside jokes and offensive language can explode online through new, quickly evolving outlets, where it can live on and be seen by thousands. The aftermath can ruin reputations, jeopardize jobs, ­disrupt classrooms and lead to lawsuits or criminal charges.

The controversy that flared last week in Rogers over a student’s inappropriate tweet about a teacher was the latest example of the phenomenon, which has become common among high schools but still catches some administrators and parents by surprise.

“It’s really natural for teens to want to be able to express whatever they want without being held accountable for it,” said Shayla Thiel-Stern, an assistant professor at the University of Minnesota who studies youth and social media. “Teachers, parents, adults in general can tell them over and over again to manage their digital footprints, but they still don’t always think it applies to them.”

The result is a frustrating game of cat-and-mouse for ­parents, who fear that teens might make a very public, and long-lasting mistake. Schools, meanwhile, need to maintain a positive environment, while trying to teach impulsive teens how to safely use technologies that can spiral out of their control.

While many adults have learned to watch Facebook, teens are moving to Twitter, Instagram and Snapchat. And anonymous outlets, like the website ask.fm and parody Twitter accounts, offer a tempting but not foolproof veil for teens who know they shouldn’t put their names to inappropriate comments. Those accounts, such as @612confessions on Twitter or the now shutdown “Rogers Confessions” on ask.fm can quickly become cesspools of profanity and sexually explicit language.

“There definitely are ­people that tweet stuff that’s not appropriate,” said Matt Miller, 18, a senior at Cretin-Derham Hall. “I personally don’t because it’s scary to me what the school would see.”

Social media in school

Jim Barnhill, a special education teacher at Minneapolis South High School, sees the fallout from smears on social media.

“The problem immediately comes into the classroom. There’s a huge emotional upheaval that takes place,” he said. “It’s unbelievably time consuming. We lose a lot of learning every year to cyber issues.”

But just what schools can do to stop inappropriate posts is still unclear. Disciplining students for online commentary can violate the right to free speech, said Raleigh Levine, a professor at William Mitchell College of Law who teaches First Amendment and media law.

“With the rise of social media and the quickly changing nature of social media, more and more schools are reaching out to discipline students for speech that takes place off campus but online,” Levine said. “It’s really important that the courts and the schools have some guidance on just how far the schools can reach.”

Justin Patchin, co-director of the Cyberbullying Research Center, regularly gets inquiries from schools dealing with troubling online accounts. Sometimes, he said, if the person behind an abusive account (such as a malicious Twitter confessions site) doesn’t voluntarily shut it down, schools can turn to the social networks themselves for help because the site might violate the ­network’s terms of service.

“It really depends on the ­circumstances and what’s being said,” Patchin said. “There are lots of examples of things that are offensive to me, or upsetting to me, but Facebook says are free speech.”

But sometimes the online activity veers clearly into criminal territory.

Dakota County Attorney James Backstrom said ­sexting (exchanging nude photographs) among minors is child pornography and online exchanges can lead to harassment or even terroristic threat charges in some cases.

His office prosecuted four teens in 2012 after students at Century Middle School in Lakeville made a game of snapping photographs of girls’ buttocks while they were in the locker room, then circulating the pictures. The teens were sentenced to probation and community service.

“We want to make sure we educate kids, not lock them up for making dumb decisions,” Backstrom said.

Parents pursue online

Sara Wedell of Otsego joins the networks her 16-year-old twins join and talks to them about what they do online. She also Googles them once in a while.

But she understands that jumping into social media can be intimidating for parents. “I almost feel like to educate the kids, we need to educate the parents on the technology we’re using,” she said.

High school freshman Leahy Schultz, 14, of River Falls, Wis., said she welcomes advice from parents and teachers, but doesn’t think parents should have full access to their kids’ accounts. “They should talk to their kids about where they’re going and how safe it is.”

That’s been mom Molly Buck’s approach. She spotted an anonymous “confessions” Twitter account for Apple Valley High School while tracking her teens social media chatter. “I followed that in a heartbeat and told other parents it was out there,” said Buck. However, she was “pleasantly surprised” to see the account was used mostly by student expressing admiration or encouragement, albeit anonymously.

Before he tweets, Kjell Hokanson, 16, of Golden Valley thinks about how it could affect his college career, his parents’ opinions and other people.

“As a teen you have to decide for yourself,” Hokanson said. “You make the final decision on what you do.”