Katie Couric plays cruel April Fools' joke on TV host

LOS ANGELES -- Katie Couric pulled off an epic April Fools' Day prank on Late Late Show host James Corden.

As Corden was introducing her, "Katie" took a nasty fall down the stairs of Studio 56.

A horrified Corden rushes to her aid, only to find it was all a prank and the woman who took the tumble down the steps was Couric's "stunt double."