What you say on Facebook could land you in jail. That's the tough lesson that a Texas teenager learned in February, when an online argument with a friend led to his arrest. He's now awaiting trial and faces eight years in prison.

Everything started when the teenager, Justin Carter, then 18, was playing an online game of "League of Legends." After the match, Carter and a friend got into a heated argument on Facebook.

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"Someone had said something to the effect of 'Oh you're insane, you're crazy, you're messed up in the head,’ to which he replied 'Oh yeah, I'm real messed up in the head, I'm going to go shoot up a school full of kids and eat their still beating hearts,'" Carter's dad Jack recalled in an interview with ABC's affiliate KVUE. "The next two lines were lol and jk."

Despite the "lol" and "jk" at the end of the post, a woman in Canada thought the post was serious enough that she called the police after finding out that Carter's old address was close to an elementary school. Carter was later charged with making a "terroristic threat" and arrested. He has been in jail since March 27. His trial is set to begin July 1.

Carter's mother has started a Change.org petition to have him released and change the anti-terrorism laws that landed her son in jail.

"Release Justin Carter from jail," reads the petition. "Too many teenagers are being arrested, jailed and having their lives forever altered because of anti-terrorism laws and investigations that impede their First Amendment right to freedom of speech."

Mashable composite, images via iStockphoto, Calamusdesign, and chipstudio.