Conversation between my wife and me.
Wife from across the room, "You are looking at those funny spinning shapes on that forum again aren't you?"
Me sat at computer, "How did you know that?"
Wife, "Because your mouth is wide open, a glazed look in your eyes and you are shaking your head."
Me, "Can you guess at everything I'm watching just by the state of my face?"
Wife, "Yes of course"
But seriously, this is so clever I'm gobsmacked.