Some knock-knock jokes which I've created, inspired by those on http://www.ahajokes.com/

Knock Knock
Who’s there?
Singapore!
Singapore who?
Singapore of sixpence!

Knock Knock!
Who’s there?
Russia!
Russia who?
Russia as soon as you can!

Knock knock!
Who’s there?
Handel!
Handel who?
Handel the glass with care!

Knock knock!
Who’s there?
Bach!
Bach who?
Bach off!