Funniest Knock knock jokes

Some funniest and short knock knock jokes to laugh about. Quick definition of knock-knock joke:

1. The punster: Knock, knock!
2. The recipient: Who's there?
3. The punster: a response, sometimes involving a name
4. The recipient: a repetition of the response followed by who?
5. The punster: the punch line, which typically involves a punnish misusage of the word set up during the response.