Be good, behave, be nice
The dragon won't think twice
'Cause bad kids pay the price
They're eaten up like mice
— Children song
A centuries-old story, with accompanying children song, The Dragon & The Mice tells about a group of mice living in a dragon's lair or kitchen. Many variations exist, without clear knowledge on what the original story was like. It's even possible that the story originates from the merge of multiple different stories. However, the most popular versions all include the same details.
The Story
When the dragon finds out the mice exist, it threatens to kill them all if they get in its way or try to flee. Later on the dragon changes its mind and allows the mice to clear out its scraps. But over time it starts demanding services, wanting the mice to find small spots and gather stuff for the dragon. It holds their families hostage and kills some whenever one of the mice fails to deliver.
The mice realize the chores are becoming harder and harder, so some plan an uprising. At night, they try to cause a rock collapse on top of the sleeping dragon. Yet the dragon expected this and eats the conspirators. It then chases the other mice, eating them one by one. Knowing the dragon will catch them all eventually, the remaining mice trigger the rock collapse while they're underneath it, so that the dragon can't eat them. Enraged, the dragon destroys the entire mouse lair, which causes another collapse and kills it.
Morale
There are various interpretations people attach to the story, often depending on the precise telling of the details. Sometimes parents use it to warn children to behave, or else they may end up eaten by monsters. This interpretation is what the children song follows, warning children to be good, or else they will get eaten like mice.
Others use it to refer to suffering under bad authority. An uprising will only lead to death, yet at the same time sticking around will merely lead to a slower demise instead. So while one shouldn't try to rise up against bad authority, it is best to never get caught being ruled over by wicked people.
There's a very sinister message behind this one! To me, it says a lot about the values of the society that made it-- which I'd love to know more about. The rhyme also scans really nicely.