NEW YORK (AP) -- Are you ready for Grandpa Charlie? Charlie Sheen tells David Letterman he'll soon be a grandfather. Sheen says his daughter Cassandra is pregnant. He told Letterman last night, "She's like married, go figure that one out." Sheen says with him going to be a grandfather, "it's like the world's going to crack in half." Sheen's FX series "Anger Management" returns Thursday night.