Knock! Knock! Who’s there? Stopwatch…

Knock! Knock! Who's there? Owls say. Owls say who? Yes, they do.

Knock! Knock! Who's there? Andrew! Andrew who? Andrew a picture!

Knock! Knock! Who's there? Spell Spell who? W-H-O

Knock! Knock! Who’s there? A broken pencil. A broken pencil who? Never mind, it’s pointless.

Knock! Knock! Who's there? Cereal. Cereal who? Cereal pleasure to meet you!