Imagination.
Pupil: Well you keep saying that things go in one ear and out the other so I am trying to keep them it all in!
It's sure as hell not a bar-mitzvah, those things are expensive.
The man on the moon? Santa Claus? Or an honest Lawyer? Yes you got it Santa. The other two are figments of the imagination.
A pigment of your imagination.
Oh yeah. Imagination.