...for saying that Rep. Cynthia McKinney looks like a "ghetto slut".
Here's the story from Media Matters...
Summary: Commemorating the third anniversary of his MSNBC show, Keith Olbermann devoted a segment to his long-standing rivalry with Fox News host Bill O'Reilly; Olbermann aired a compilation of clips mocking O'Reilly. He also declared radio host Neal Boortz that evening's "Worst Person in the World" for saying that Rep. Cynthia McKinney (D-GA) "looks like a ghetto slut."LINK: Olbermann marked third anniversary by devoting segment to "O'Rivalry"; declared Boortz "Worst Person" for saying McKinney "looks like a ghetto slut"
Olbermann's segment on O'Reilly is quite funny.