Have you played the game BANG before? BOO! works in the same way. Place all of the cards in a container. Set a time for 10 minutes. Take turns choosing cards and saying the words on the monster cards. If you get the ghost, everyone yells BOO! The person who drew the ghost card puts all of their cards back in the container. The student with the most cards at the end wins.
BOO! has targets the following sounds using Halloween themed vocabulary: