If you understand, say "understand".
If you don't understand, say "don't understand".
But if you understand and say "don't understand".
How do I understand that you understand? Understand!

If two witches were watching two watches, which witch would watch which watch?

Swan swam over the sea,
Swim, swan, swim!
Swan swam back again
Well swum, swan!

A flea and a fly in a flue
Said the fly "Oh what should we do"
Said the flea" Let us fly
Said the fly"Let us flee"
So they flew through a flaw in the flue