You know those signs that tell you not to joke about bomb threats in airport security lines? They’re no laughing matter. And apparently they extend into the Twittersphere–at least in the UK, where a 27-year-old accountant posted the following upon discovering that airport was closed,Crap! Robin Hood airport is closed. You’ve got a week and a bit to get your shit together otherwise I’m blowing the airport sky high!! Whoops. The accountant, one Paul Chambers, was arrested back in January following his “foolish prank.” He was convicted for the perceived bomb threat and fined £1,000 ($1,615) over the summer. In an followup hearing held this week, Judge Jacqueline Davies upheld the original ruling on all accounts. The judge read the offending tweet aloud, adding that Chambers surely knew that the joke might have been taken as a serious threat.