A fanciful re-telling of the fairy tale Jack and the Beanstalk. The golden goose has been replaced with a hen, and the cow with a beat up old car (a Tin Lizzie).
The explosion at the end is a rendition of the mushroom clouds associated with the first atomic bombs, which were first dropped at the end of WW2.
Used car dealers often had gimmicks to draw customers in, such as California's Cal Worthington and his exotic pets.