MTV REPORTS  Fat Joe has had his fair share of rap beefs, but he’s taking his battle with Uncle Sam very seriously. The veteran rapper is facing jail time on charges that he failed to pay taxes on approximately $3 million in income in 2007 and 2008. “I can’t really explain that ’cause I got a real court case going on, like facing jail time. But I guess after June 24. Hopefully, it goes well,” Joe said on Wednesday (May 22) on “RapFix Live.” LAURYN HILL GETS 3 Months in Jail for Taxes Unpaid  Back in December, the “Make It Rain” MC pleaded guilty to the charges against him and has been working…