English Joke

Most known joke of English about like 'knock knock' and 'blonde'. I still can't totally understand the funny of knock knock joke, I think that could be different of culture. 

Learning language is learning new culture so I submit the Joke of Day for My igoogle page. .

Some of that are so joking and most of it are translated in Chinese that i was read this before at internet forum or Reader Digest.

Knock Knock Joke always present in the form.
'knock knock'
'who is?'
'Yard'
'Yard who?'
'Yahoo~~oo'

Well, It's not very funny at all but this's my original by the standard K.K joke. I can't imaging that if I tell the joke for my friend. it's really embarrass in no reaction so call the cold joke, freeze the everybody.