Ah, ye ol' knock knock jokes!

Knock Knock
Who's there?
Abbott!
Abbott who?
Abbott time you answered the door!
Knock Knock
Who's there?
Ada!
Ada who?
Ada burger for lunch!
Knock Knock
Who's there?
Acid!
Acid who?
Acid down and be quiet!

Knock Knock
Who's there?
Agatha!
Agatha who?
Agatha headache. Do you have an aspirin?

Knock Knock
Who's there?
Alaska!
Alaska who?
Alaska my friend the question then!

Knock Knock
Who's there?
Alba!
Alba!
Alba in the kitchen if you need me!