On the verge of 3, my son is finally old enough to trick-or-treat this Halloween. He understands wearing a costume and knocking on doors. He’s been practicing saying “Trick or treat!” and “Boo!” to our neighbors’ ghosts and pumpkins that have been out since early September. He’s pointing out all the skeletons and witches he sees. Every day — no, every hour — he gives me a different (yet adamant) declaration of what he’d like to be for Halloween.