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Navid Farsi, the man who threw sugar on Adam Levine, and who had previously thrown a rock at Dwayne "The Rock" Johnson, pled no contest to one count of battery and was placed on three years' summary probation, 20 days' Caltrans service (road work for the State of California, Department of Transportation), and 52 psychological counseling sessions.
As part of the deal, Farsi also must stay 500 yards away from red carpet events, premieres, entertainment shows, and both Adam and Dwayne.
Luckily, Adam wasn't hurt, but it's pretty scary when his availability to fans can be abused like this. Better to ask for an autograph than to throw stuff.