The Stage is a room in CP3D, located to the right of the Pet Shop and the left of the Pizza Parlor at the Plaza. It holds different plays every few months. The Stage is commonplace for penguins to make a product or spread their imagination. The Costume Trunk catalog can be found here, which contains costumes and a background for each play.
In every play, excluding Night of the Living Sled: Live, there is a live performance of the play done by NPC penguins every 6 hours. When a player sits through the entire performance, they are rewarded with a free item. Ruby and the Ruby is the only play to have not given out a free item.