There was a goat who was a donkey's servant, but the donkey was a gentle master, so the goat decided to take advantage of the donkey's mild temperament.
"I'll show him who's really the boss!" said the goat, and he got up on top of the donkey and tried to ride him like a horse.
This made the donkey angry so he reared up on his hind legs and threw the donkey onto the ground. Then, as he trampled the goat under his hooves, the donkey said, "Even if your master is a donkey, you shouldn't try to ride him."
Inspired by: Mille Fabulae et Una, a collection of Latin fables that I've edited, free to read online. I am not translating the Latin here; instead, I am just telling a 100-word version of the fable.
Notes: This is fable 324 in the book, which is Perry 623.