Private Thoughts Made Public

Here’s a little snippet from a conversation I had with my son this evening:
Son: “Dad, come over here and help me build a Lego robot!”
Me (reading the newspaper): “H’mmm….. yeah…… ok”
Son: “Come on!”
Me: (still reading): “Mmmm”
He then gets up, walks over to me, puts his hand to my temple and pretends to flick a switch, providing a neat little clicking sound effect as well.
Me: (looking up from newspaper): “H’mmm?”
Son: “Now your brain is switched on, you can move. Come on!”
After that, what alternative did I have?