Bearzerk is an evil robotic teddy bear who is the final boss in Pac-Man Party. His name a pun on the word "beserk". Bearzerk was originally a toy bear that had a wall in front of it with a plate of jelly beans in front of the wall.
However, the players will take and eat the jelly beans that are on the plate. Soon all the jelly beans will be gone, and the next player that passes the teddy activates a cutscene with Bearzerk wimpering, then turning into its robot form.