Mr. Blop's head contains a variety of colored balls. Each color belongs to a different player. When Blop's tongue is pressed, a ball pops out of his hat and players try to catch it, if it is of their color. The object of the game is for a player to collect four balls of his color. The one white ball is wild and counts as any color. The one black ball allows its catcher to penalize an opponent and put back one of their caught balls. - BoardGameGeek