 " <unk> Mouth " was directed by Andrew <unk> , and was written by Walt <unk> , Paul <unk> , and <unk> Williams . <unk> and <unk> also served as storyboard directors , and Carson <unk> , William <unk> and Erik <unk> worked as storyboard artists . Series creator Stephen <unk> has described the episode plot as " a classic thing all kids go through . " Much of the storyline for the episode was inspired by the writers ' own experiences from childhood . The episode originally aired on <unk> in the United States on September 21 , 2001 . The episode marks the introduction of Mr. <unk> ' mother , Mama <unk> , who was voiced by former <unk> <unk> creative producer and current executive producer Paul <unk> . 
