Sheila: Knock knock!
Berger: Who's there?
Sheila: No, I'm not doing a knock-knock joke.
Berger: ...No I'm Not Doing A Knock-Knock Joke who?
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Sheila: Knock knock!
Berger: Who's there?
Sheila: No, I'm not doing a knock-knock joke.
Berger: ...No I'm Not Doing A Knock-Knock Joke who?
HAIR Headcanon
This takes place after the musical and quite a while after Claude dies in Vietnam.
Berger and Sheila have a baby boy together. They name him “Claude Jr.” in memory of Claude. He grows up acting a lot like the person he was named after. Also he becomes friends with Jeannie’s kid.