There's no sweeter sound than a giggling child. Up the laugh factor with some knock-knock jokes for the youngest comedians.

About a year ago, I thought it might be fun to teach my girls (then 4 and 2) some knock-knock jokes. Oh brother. They caught on pretty quickly to the technique, but their style still needs a little work. We depend pretty heavily on joke books and the Internet for new material, though after a few minutes it slides into various versions of their favorite knock-knock joke, kind of like this one:

Knock, Knock

Who's there?

Mama.

Mama who?

Mama aren't you glad I didn't say Daddy?

Sigh.

If you've got a little one with a sense of humor and you're feeling brave, here are some websites to get you started:

NIEHS Kids Pages

Families.com

Backyardigans Knock-Knock Coloring Pages

Finally, a family favorite:

Knock, Knock

Who's there?

Olive.

Olive who?

Olive you! (I love you.)