Knock! Knock! Who’s there? Rhino…

Knock! Knock! Who's there? Goliath. Goliath who? Goliath down, thou looketh tired!

Knock! Knock! Who's there? Opportunity That's impossible. Opportunity doesn't come knocking twice!

Knock! Knock! Who’s there? Leaf Leaf Who? Leaf Me Alone!

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

Knock! Knock! Who's there? Ferdie! Ferdie who? Ferdie last time open this door!