Sept. 8 (Bloomberg) -- President Barack Obama has some counsel for youngsters who want to grow up and be president: be careful what you post on Facebook and other Internet outposts.

Obama offered, what he called some “practical political advice” to a 9th grader at Wakefield High School in the Washington suburb of Arlington, Virginia, who asked how he too could become President one day, saying that “when you’re young, you know, you make mistakes and you do some stupid stuff.”

“I want everybody here to be careful about what you post on Facebook, because in the YouTube age whatever you do, it will be pulled up again later somewhere in your life,” Obama said. “That’s number one.”

His remarks preceded a speech to students at the high school that was broadcast to schools across the country, in which he urged them to “get serious” about their studies and take responsibility for their own success.

Representatives from Palo Alto, California-based Facebook Inc. did not immediately respond to a request for comment.

The social networking tool that was founded in 2004, has more than 250 million active users, with more than 30 million of them posting status updates at least once a day, according to Facebook’s website.

In the question-and-answer session with the 9th grade class, which wasn’t broadcast, Obama said he’s heard stories about Facebook postings hindering job applicants.

“I’ve been hearing a lot about young people who, you know, they’re posting stuff on Facebook, and then suddenly they go apply for a job,” Obama said to laughter.

To contact the reporters on this story: Julianna Goldman in Washington at jgoldman6@bloomberg.net; Kate Andersen Brower in Arlington, Virginia, at Kandersen7@bloomberg.net

Last Updated: September 8, 2009 13:21 EDT