Hi guys,

does anybody know, what's the big deal with knock-knock joke? I heard it a lot of times used in action, but I still don't get it…Why is everybody laughing?

For people, who don't know what I'm talking about:
<a>Knock-knock!
Who's there?
<a>[The name].
[The name] who?
<a>[not funny answer, that I don't get]

Any ideas?

Well, good question. After a little investigation via Google you can get a lot more than I can offer. For what it's worth, check this out:

The knock-knock joke is a type of joke, probably the best known format of the pun, and is a time-honoured „call and answer“ exercise.

It is a roleplay exercise, with a protagonist (the punster) and an antagonist (the recipient of wit). Developmental psychologists study knock-knock joke usage in younger children as it provides valuable insight into how children advance their language skills.

The standard format has five lines:

The punster: knock-knock (indicating a door has been struck to gain attention)
The recipient: Who's there? (an enquiry)
The punster: a response, usually involving a name (to set up the pun),
The recipient: repeat the response, adding who? – a request for clarification
The punster: the punch line, which inevitably involves a punnish misusage of the word set up during the response.

And now for the conclusion I would like to share some of my favourites:

Knock, Knock.
Who's there?
Nobel.
Nobel who?
No bell, that's why I knocked!

Knock knock
Who's there?
Doris
Doris who?
Doris locked, I'm coming in through the window!

Knock Knock
Who's there !
Ice cream !
Ice cream who ?
Ice cream if you don't let me in !

Will you remember me in an hour?
Yes.
Will you remember me in a day?
Yes.
Will you remember me in a week?
Yes.
Will you remember me in a month?
Yes.
Will you remember me in a year?
Yes.
I think you won't.
Yes I will.
Knock knock
Who's there?
See–you've forgotten me already.

PS: Just for the record, I'm not saying that these make me ROFL but they are kinda funny. Knock knock jokes are plenty and in order to understand them you have to possess the necessary vocabulary and imagination.

If they are supposed to be „kind a funny“ and not „ROLF“, then OK. I asked, because I heard a lot of times, how Knock-Knock joke made people „ROLF“. Response has never seemed as „kind a funny“.
Anyway, thanks Mato.