jbieberhotel032911_01_X17%20copy.jpgJustin Bieber will appear in a Nassau County public service announcement on "internet responsibility" as part of a plea deal for causing a mall riot in Garden City, NY in 2009.

More than 3,000 screaming fans created a "dangerous situation" in the mall, causing cops to ask Bieber's manager, Scott Braun, to take down his Tweet encouraging fans to show up.

Braun refused to Tweet the event had been cancelled, and cops immediately took him into custody.

Who knew you could get arrested for NOT Tweeting? That's gotta be a first!

The Baby singer's PSA will play in Nassau County schools, and the costs will be covered by the Bieber's Island Def Jam Record Music Group.