Assassination attempts against the president are no Twitter-joking matter. Make the threats in the city that President Obama will be attending for a political convention— like 21-year-old Donte Jamar Sims did — and you’ll likely end up in jail.

Claiming to be high on marijuana at the time, Sims posted five tweets threatening assassination. He reportedly admitted to the tweets when officers visited his home and wrote an apology at the police station. The judge ordered Sims, who faces five years in prison and a $250,000 fine, detained until trial because of his criminal past.

UPDATE, Sept. 8: The Secret Service visited 16-year-old Alyssa Douglas (@Alyssa_Douglas) after she tweeted an assassination wish for President Obama. The Clarksville, Ohio, student said “someone needs to assassinate Obama … like ASAP” and included a vulgar hashtag in her tweet.

“These things are so readily available to young people; they don’t fully understand the consequences of what they say,” said  Jeffrey Blevins, head of the University of Cincinnati’s Department of Journalism. “It’s not just a snide comment to a couple of their friends where the friends can read that remark in context. Instead, that comment goes out to the entire Twitter universe, and you lose control of it. That concept is very difficult for young people — and even some adults — to understand.”