Z: Dad, I'm afraid of the snakes under my bed.
Me: You know what to do. You need to send Rikki Tikki Tavi under there. You need a mongoose.
Z: But Rikki Tikki Tavi isn't real.
Me: Neither are the snakes under your bed.
Z (after thinking this through for a minute): Dad. I'm afraid that sabre-tooth tigers are going to sneak up on me.