Knock knock. Who's there? Olive.

Olive who? Olive your jokes are so funny!

Knock knock. Who's there? Fig.

Fig who? Fig-ure it out yourself!

Knock knock. Who's there? Figment.

Figment who? Figment of your imagination, but I'm real and I need to come in!

Knock knock. Who's there? Cows go

Cows go who? No, cows go 'moo'