Thank yourself

Morning rush hour. 

Pia was spreading peanut butter on her bread in  extreme slow motion.  Daddy gets impatient, grabs the butter knife from Pia, quickly spreads butter on his bread, then hands back the knife to Pia:

Daddy: Thank you.

Pia: Daddy, don't say thank you to yourself.

Daddy: I was saying 'thank you' to you.

Pia: But I didn't give you the knife. You took it from me.

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