The Crooked World was a planet of fabric. Beings which inhabited it could be shaped by the thoughts of visitors to the world.
A human girl crashed on the planet in an escape capsule and starved to death within days. The child's thoughts and memories shaped the planet into a cartoon world, populated by cartoon characters who lived their lives in a meaningless, repetitive existence. When the TARDIS arrived on the planet, the Eighth Doctor and his companions accidentally gave the inhabitants free will. (PROSE: The Crooked World)