"I Don't Know"

[Laura used to sing a song when she was a kid to bug her brother that she made up called "I don't know". I heard this for the first time recently.]

Jack: "I wonder if my phone is downstairs..."
Laura [singing her song]: "I don't know, I don't know. If you ask me, what I'll tell you is that I don't know."
[Jack just looks at her, surprised.]
Laura: "Go ahead. Ask me something."
Jack: "If you're just going to answer 'I don't know' why would I ask you?"
Laura [singing triumphantly]: "I don't know!"