Judge James Cross of Crown Court in Newcastle, England sentenced Reece Elliot, 24, to two years and four months in prison for threatening to kill students at Tennessee's Warren County High School, the BBC reported Tuesday.
Elliot was accused of using a false name to post the threat in February on memorial pages for two Tennessee girls killed in car accidents.
As a result, some 3,000 pupils in Warren County missed school the day after the threats were posted.
Elliot pleaded guilty to making a threat to kill and eight counts of sending grossly offensive messages.
In sentencing Elliot to jail, Judge Gross called his threat "no more than self-indulgent nastiness."