Most teens know the main rule for protecting themselves on the Internet: “Don’t post anything your parents wouldn’t like.” But is that really reality?

No. If every teen actually followed that rule, everyone would have a perfect online reputation.

For most teenagers, a bad representation means posting inappropriately with cursing, videos of fighting, half-naked photos and anything incriminating that involves drugs and violence. Some teens post things they shouldn’t on purpose, simply because they want someone to look at it.

T.J. Neely, a former gang member in Minneapolis, said he used to post damaging information because he wanted the image of “a big dog who was down with anything.” Now 25, he limits the number of friends in his network and only posts positive thoughts.

Phil Trout, a college counselor at Minnetonka High School, advises students beginning in grade 11 that they should have a professional-sounding e-mail address and a “Facebook page that’s a good public relations statement about you.”

However, many students don’t follow his advice.

“In an emotional moment, they post something they’d like to have back,” Trout said.

There are numerous examples of teens who’ve faced repercussions for what they’ve posted online. Mattayo Goodman, a freshman at North High School in Minneapolis, said his cousin posted a picture of himself pointing a gun, which resulted in expulsion from school for a year. On the beach at Lake Calhoun in Minneapolis, 15-year-old Hugh Cashman from Edina described a teen from his school who posted a picture of himself smoking with Rastafarians in Jamaica. The teen was suspended and kicked off a sports team.

While that might seem a little extreme to teenagers, it’s not in the eyes of a school or sports team. After all, you’re representing them, not just yourself. How you represent yourself online reflects on your parents, your school, your team, even the company you work for.

Dave Eisenmann, director of instructional technology and media services for Minnetonka Public Schools, said some employers ask job candidates to show them their Facebook pages at job interviews.

Colleges also check out online reputations. Eisenmann’s sister-in-law works in a college admissions office in Pittsburgh, Pa. When they have more candidates than they can take, all with similar credentials, the admissions officers will sometimes check out the applicants’ online reputations using a Google search and decide whom to admit based on what they find.

So why go online if you can’t really be true to yourself? There are ways to strike a balance.

For one, simply don’t post anything that can adversely affect your future. Cashman protects himself by keeping his Facebook page private and letting his dad see what he’s posting.

If you don’t want to friend your parent, Amanda Lenhart, a senior researcher for Pew Research Center’s Internet & American Life Project in Washington, D.C., suggests having an older person you trust, like an aunt or older brother, monitor what you post.

Other helpful hints: If someone posts something you don’t like, simply ask them to take it down. If someone tags you in an embarrassing photo, untag yourself and change your settings to prevent people from tagging you in the future. If you’re angry with someone, talk to him or her in person rather than adding to online drama.

Also, remember that what you post online isn’t gone forever just because you click the delete button. The Library of Congress has started saving tweets as part of America’s historical record, Eisenmann said. By law, schools have to save information from school Gmail accounts for three years.

In a national survey of teens published this spring, Lenhart found that teens are getting smarter about online privacy. Six of 10 teens in the survey said they have set their Facebook profiles to private so that only friends can see it. Girls are more likely than guys — 70 percent compared to 50 — to keep their profiles private. Seventy-four percent of teen social media users have also deleted people from their network or friends’ list. Three in 10 have deleted or deactivated an entire profile or account.

In extreme cases, professional reputation help is also available. Eisenmann cited a service — — that will work to clean up online reputations by creating more positive content and linking to it from various websites. However, the service is expensive: It starts at $3,000 for one year.

That’s a lot of money to make sure that embarrassing photos of you don’t show up at the top of a Google search.