Top Definition
A joke made about a caller at the door. It usually ends up as a play on words.

The structure of a knock-knock joke is as follows:

Person 1: Knock-knock.

Person 2: Who's there?

Person 1: (Phrase A).

Person 2: '(Phrase A)' who?

Person 1: (Phrase A) (funny punch line).
Here is a knock-knock joke:

George: Knock-knock.

Reginald: Who's there?

George: Em.

Reginald: 'Em' who?

George: Emphysema! So you better quit smoking!
by Diggity Monkeez May 19, 2005

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Child play for quire little boys on a street corner excepting that they will turn into crackheads later on in life. Most of them have nothing to look forward to.
Come on Paul lets get some knock knock jokes up in dis joint.
by Obama leader of the Democrats December 16, 2014

The Urban Dictionary Mug

Lotsa space for your liquids.

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The Urban Dictionary Mug

Lotsa space for your liquids.

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The Urban Dictionary Mug

Your favorite word on a white mug.

Create a mug

The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

Buy the mug

The Urban Dictionary T-Shirt

Soft and offensive. Just like you.

Buy the t-shirt

The Urban Dictionary T-Shirt

Smooth, soft, slim fit American Apparel shirt. Custom printed. 100% fine jersey cotton, except for heather grey (90% cotton).

Buy the t-shirt