D and the Button

This exchange happened just a few nights ago as we were getting the boys ready for bed. Let me set the scene a bit, shall I? Boys are in their pajamas and we are armed with their toothbrushes. It's already past their bedtime. I've got J and T has D. That line reminds me of Chicka Chicka Boom Boom - but I digress. I'm brushing J's teeth and I hear the following conversation between T and D:

T: C'mon buddy. I have to brush your teeth. Open your mouth.
D: You have to push the button.
T: Oh. Which button?
D: This button. (Points to a button on his pajama shirt)
T: Oh. Ok. (Pushes button and adds a sound effect - boooop)
D: (Just looks at him)
T: (Pushes the button, again with sound effect - booooop)
D: (Just looks at him)
T: (Pushes the button again with louder sound effect - booooop)
D: It's not working.