This is a medieval looking torture chair seen in Kim Jong Il's dungeon. It's covered in fake blood and has little spikes all over it. There's also little leather straps for tying down puppets you want to torture. The part at the very top that holds the prisoner's head in place is covered with shark's teeth. The chair was made by prop maker Chris Towle for the movie (he signed his name on the bottom of the chair after making it).

Here's a couple of screen shots during the 'I'm so Ronery' song where you can see
a puppet in the background strapped to the chair.