Knock Yourself Out

(Knock-Knock Jokes to Make You Groan)

1: Knock-Knock.
2: Who's there?
1: Owl say.
2: Owl say who?
1: You're right, they do!

1: Knock-Knock.

2: Who's there?

1: Pencil.
2: Pencil who?
1: Never mind; it's pointless.

1: Knock-Knock.

2: Who's there?

1: Kanga.
2: Kanga who?
1: No...Kangaroo!

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How to end a Knock-Knock joke:

1: Knock-Knock.
2: It's open!

     When we were children and as we spent time with children when we became adults, "Knock-knock" jokes were likely part of our history, at least in the English-speaking world.   This is particularly a phenomenon in the US. 

     The roots of knock-knock jokes seem to be in 1900s humor. They started as "Do You Know?" jokes.  In less threatening, less pressured times, a jokester seeking to be funny would approach a stranger and ask a question like, "Do you know Joe?'.  The respondent was expected to reply, "Joe who?"  And the jokester would stay something like "Joe K'Ster."

     In the 1920s, fashion-forward flappers tossed out what they considered witty jokes they called "nifties."  Some of them were structurally similar to the "Do You Know?" jokes from the turn-of-the-century. 

     Knock-Knock jokes started in the 1930s. Some sources trace the origin to Frank Knox, running mate of Republican Alf Landon in 1936.