Craig Ferguson knows how to turn almost any topic sexual. He caught Maria Bello off guard with a conversation about the infamous hat she wears on 'Prime Suspect.' She brought the hat with her on 'The Late Late Show' (Weeknights, 12:37AM ET on CBS), where she put it on Ferguson's head.

He thought it made his head look huge, so he put it on hers. He'd said earlier that he thought she had a lovely head, but he liked it with the hat on as well.

"It looks good," he said. "I'm surprised that you chose to wear a hat, because you're famous for your head."

He said it so deadpan, she actually took him seriously for a moment, wondering about it before realizing what he was really saying and smacking him deservedly with the hat.