An old man set out to go into the woods, although he didn't know what for. Then he came back and said:
-- Hey, old woman, you!
The old woman fell straight down. Since then, the hares are white in winter.
By Russian absurdist writer Daniil Kharms, this may just be the shortest fairy-tale ever.
Kharms, best remembered as a children's writer, was a prominent member of the Russian avant-garde in the 1920s, 'subverting' literature with his illogical and fantastic stories until the Soviet censors intervened and he was exiled.
Around the same time, also in St. Petersburg, Vladimir Propp in his 'Morphology of the Folktale' reduced the fairy-tale to a set of 31 structural elements. I don't know if Kharms knew Propp, but it's tempting to read his fairy-tale as a parody of Propp's rigid analysis...
The Absurdist Collective has a collection of Kharms stories in English.