I had the pleasure of taking my 2-year-old son out trick-or-treating this year and it was incredible. You could literally see him piece together, in his mind, that this day was something special. He couldn't believe that there were a bunch of other kids, all dressed up, walking around the neighborhood acting just as silly as him.
There was also the wonderment, as he went door to door, discovering that people were literally giving him candy for free. It was amazing.
I only wish I put on a costume to go trick-or-treating with him, something I've got planned for next Halloween already. But after seeing Justin Timberlake, Jessica Biel, and their son Silas' coordinated Pixar costume effort, I think I've got to get my game up.