Charlie Sheen to be a grandfather, daughter Cassandra Estevez is pregnant

Charlie Sheen made kind of a big announcement on "The Late Show with David Letterman" Monday night (Jan. 14).

"You are going to be -- fill in the blank -- you are going to be in the next couple months ..." prompts Letterman.

"A grandfather!" says Sheen.

"My daughter Cassandra. And she's like married," the actor laughs. "Me as a grandfather, it's like the world's gonna crack in half. This is not a title I'm ready to adopt."

When Letterman says being a grandfather is great, Sheen cracks, "Well, yeah, 'cause you can leave the kid!"

The daughter of Sheen's in question is Cassandra Jade Estevez (pictured above in 2000), Sheen's 28-year-old daughter with his high school girlfriend Paula Profit. Sheen has four other children: girls Sam and Lola with Denise Richards and twins Bob and Max with Brooke Mueller.