Knock Knock, who's there?

One of the first jokes I heard told at school was a Knock knock joke.

Knock Knock
Who's there?
Amos
Amos who?
A mosquito.

Oh how we laughed at that joke and it was our first awareness of the power of words to cause laughter. Everybody has their favourite Knock Knock joke and while writing my post about London I remembered one of mine.

Knock Knock
Who's there?
M:A:B is a big horse
M:A:B is a big horse who?
M:A:B is a big horse I'm a Londoner, (Maybe it's because I'm a Londoner)

These jokes will be coming thick and fast now, because once you start you can't stop

Knock Knock
Who's there?
Sam and Janet evening
Sam and Janet evening who?
Sam and Janet evening, you will find a stranger, go to him....
Some enchanted evening ......

Knock Knock
Who's there?
Little old lady
Little old lady who?
I didn't know you could yodel.

Knock Knock
Who's there?
Eileen Dover
Eileen Dover who?
Eileen Dover and fell in ( I leaned over and fell in).

Probably what makes us laugh at these jokes is they are really silly ....