This Is My Life
Parent 1: Knock Knock
Parent 2: Who's there?
Parent 1: Interrupting Child
Parent 2: Interrupting Ch--
Child: Mama!
(Seriously, though, Rosie has discovered Knock Knock jokes, as well as jokes in the form of "What did one ____ say to the other ____?" -- If you have any you suggest we teach her, please add them in the comments.)

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http://www.amazon.com/gp/product/0800788036
It looks like it has stuff for kids from ages 5-10, so you may get a bunch of use out of different sections on different years.
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Who's there?
Juno
Juno who?
Juno where I can get a hug?
Rosie can invent her own answers too.
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Who's there?
Needle.
Needle who?
Needle liddle TOES in my mouth! [Rapid inversion combined with NOM NOM NOM as appropriate.]