Possly the cleverest or funniest knock-knock joke ever created. But you might not get it.

Knock-knock.
Who’s there?

Knock-knock.
Who’s there?

Knock-knock.
Who’s there?

Knock-knock.
Who’s there?

Knock-knock.
Who’s there?

Knock-knock.
Who’s there?

Knock-knock.
Who’s there?

Knock-knock.
Who’s there?

Knock-knock.
Who’s there?

Knock-knock.
Who’s there?

Knock-knock.
Who’s there?

Knock-knock.
Who’s there?

Knock-knock.
Who’s there?

Knock-knock.
Who’s there?

Knock-knock.
Who’s there?

Knock-knock.
Who’s there?

Knock-knock.
Who’s there?
Philip Glass.

• Joke by the photo-realist artist Chuck Close