While Chris Brown had a solemn presence in the Los Angeles courtroom where he received the sentence for his February assault of Rihanna, the 20-year-old singer was partying hard at a dance club just hours later. PEOPLE reports that Brown left his court hearing and headed straight to Guys & Dolls with a bunch of his friends and bodyguards, entertaining the crowd by dancing to Michael Jackson's 'Dirty Diana.'

"He didn't seem to care at all that everyone was watching him," a source told the magazine.