Historical origin Skull-shaped whistle found in the ruins of Aztec civilization Also known as the death whistle, the roar whistle Death sentry is used for psychological warfare. In the war, when hundreds of death whistle sounded, The enemy feels like an undead army composed of zombies, skeletons and various monsters in the underworld, screaming, shouting and whistling, making the enemy feel frightened. Archaeologists believe that the Aztec death whistle was used to guide sacrifices.