Obama's "Bernie Mac Moment"?

On Friday night, the comedian Bernie Mac, a longtime friend and supporter of Senator Barack Obama, set out to entertain a crowd at a $2,300-a-head Obama fund-raising event with humor touching on issues like menopause and prostitution. But by the time Mr. Mac was wrapping up his remarks, some in the crowd had turned on him, and when Mr. Obama took the stage, he told the comedian to “clean up your act.”