Halloween Whistles (48 Pieces) Plastic Make some noise with these 4 1/2" fun plastic Halloween whistles. Form a jam band from these instrumental green monsters, ghosts, pumpkins and more! Play a colorful medley of monstrous music with your friends and guests at the costume party! Drop them in trick-or-treaters bags for a sweet surprise!Plastic Halloween Whistles. 48 Pieces. Assorted styles.