The Manciple's Prologue
The Manciple offers to tell a story in place of the cook, who is quite drunk.
Phoebus Apollo, before he lived on Olympus, had a white crow that could speak like any human on Earth. He loved the crow, and was very jealous of her. One day, Phoebus' wife was fooling around with her lover when he was gone, and when Phoebus returned, the bird sang "cuckoo!"
A play on the world "cuckold" which means a husband of an unfaithful wife. Phoebus was upset, and so he killed his wife, and cursed the crow by pulling out its white feathers leaving only black, and taking away the crow's ability to sing.