Definition from Wiktionary, the free dictionary
knock-knock joke — see knock-knock joke
- (colloquial, often childish) A phrase used to introduce a "knock knock joke"
- Knock knock./Who's there?/Wendy./Wendy who?/Wendy you want to open the door?
- (colloquial, often childish) A phrase used in lieu of knocking (e.g. on the door), when it is not possible to knock.