Pokemon - episode 64 - 23 Sep, 1998

Upon heading back to Pallet Town, Ash and his friends see a Mr. Mime trying to escape from a trainer who runs a circus. Unable to get the circus' overweight Mr. Mime to act, Ash and the gang have to find another one to take its place. The gang choose to dress up Ash so he can look like a Mr. Mime. Meanwhile, the Mr. Mime from earlier comes to the Ketchum residence and is mistaken by Mrs. Ketchum for Ash. (Source: Wikipedia)