Good-night

My brother in law was tucking his young and very tired daughter in bed and made the mistake of trying to talk to her.  (I'm guessing the standard questions like - did you have a good day today?)  She tells him, "Be quiet daddy, I need to go to sleep."  So he asks her if he can sing a song to her to help her fall asleep.  Her whispered reply, "I'm already asleep."