A Texas teen has been jailed since late March for what his father says was just "a dumb joke", he posted on Facebook.

Justin Carter and a friend were arguing with a third person about the online video game League of Legends, when Justin made acomment about shooting up a school.

According to KVUE, an unidentified woman in Canada who saw Justin's comment didn't realize it was intended to be a joke and tracked down the teen's address using Google.

According to Justin's dad Jack told the Austin news station, "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...The next two lines were lol and jk."

After noticing that he lived near an elementary school the woman called the cops.

Justin was then arrested and charged with making a terroristic threat — a crime punishable by up to eight years in prison.

Carter's family has since started a petition to raise awareness of his predicament, and call for a thorough review of terroristic threat laws.

Read more: Gawker

screengrab via KVUE