The Upset Stomach
WARNING! SPOILER ALERT!!
The girl in this episode is called Ethel Turnip, who could never get enough food. She wants another stomach, so she can eat twice as much food; she gets one, but refuses to wait until Christmas Morning, and opens it then and there. She names it Rover, and treats it like a dog.
Soon, however, she gets annoyed by its constant attention, so she throws it in some mud in the countryside. Rover starts to devour cows, sheep, and anything that gets in its path!
Finally, it reaches Ethel's house, so her father thinks it had indigestion, but it hadn't. It ate her, leaving only her shoes.