Betty: Black hens are more clever than white ones, aren’t they?
Mum: How do you know?
Betty: Well, the black hens can lay white eggs, but the white hens can’t lay black ones.
Only Play on the Black Notes
Jack: Mum, can I play the piano?
Mum: Not till you’ve washed your hands. They are dirty.
Jack: Oh, Mum——I’ll only play on the black notes.