| Answer | Crossword Clue |
|---|---|
| OLD | Like most knock-knock jokes |
| PUNNY | Like many "knock-knock" jokes |
| PUNS | Knock-knock jokes, essentially |
| PUNS | Essence of knock-knock jokes |
| PUN | Knock-knock joke's punch line, usually |
| DOOR | It's implicit in knock-knock jokes |
| DOOR | It's implicit in all knock-knock jokes |
| MRMOOSE | "Captain Kangaroo" character who told knock-knock jokes |
