A Pink fan went to jail for tweeting about Pink's song, "Timebomb" Jim Dyson/Getty Images 140 characters can be all you need to end up behind bars.

Over the years, more than a dozen people – mostly teenagers – have been arrested for tweeting. Most of the arrest-worthy tweets were violent, mentioning mass shootings, assassinations, bomb threats, and more.

Sometimes the intent behind the violent messages is pure. They were either sent sarcastically, or they were phrases taken out of context.

The following examples serves as reminders that everything you write on social media is public. Be careful what you say, because you're always being watched.