Tina Fey and Amy Poehler make people laugh on a daily basis. Their recent buddy comedy Baby Mama debuted at No. 1. But the ladies tell Oprah Winfrey in an interview airing Thursday that they still aren't sure if they're funny. "I think you never really know," Fey said after Winfrey asked when she knew she was funny. Quipped Poehler: "I would do serious plays and people would laugh." Apart from their hit movie, Poehler has another happy occasion to anticipate: the birth of her first child.