From Sports Illustrated- Just when you thought there couldn't be any more uncomfortable silences on "Jimmy Kimmel Live," they went out and hired Mike Tyson to be the guest sidekick last week. While Tyson was at times surprisingly chatty, he was also at times unsurprisingly vulgar. On Friday, apropos of nothing, he asked guest Michael Vartan of "Alias" if he had ever had sex with Shannen Doherty, then proceeded to wonder aloud, "Can you imagine Shannen with a big, black buck?" Another Tyson reference -- to having sex with "Alias" costar Jennifer Garner -- as well as a lengthy comment that was bleeped out left Vartan mute and looking as if he were sitting in the guest's chair against his will.