This ad to raise awareness of child abuse is brilliant.
An explanation from Gizmodo:
The secret behind the ad’s wizardry is a lenticular top layer, which shows different images at varying angles. So when an adult—or anyone taller than four feet, five inches—looks at it they only see the image of a sad child and the message: “sometimes, child abuse is only visible to the child suffering it.” But when a child looks at the ad, they see bruises on the boy’s face and a different message: “if somebody hurts you, phone us and we’ll help you” alongside the foundation’s phone number.
For Australia the number is: 1800 55 1800 for Kids Help Line.