Lay the graham crackers in a single layer on a microwave-safe plate. Heat them in the microwave for 30 seconds to 1 minute on high.
Using a metal cookie cutter, cut the graham crackers into a Halloween shape (pumpkins, bats, cats, and eyeballs without too many little details work best).
Light a hibachi on a table near your door. Make sure there is fireproof stone underneath to prevent melting things. Next to the hibachi, put some wooden skewers. Set out a tray of the marshmallows, graham cracker shapes and chocolate near the hibachi.
Encourage trick or treaters to make their own s'mores at the door!