After beating the game and unlocking all of the balloons, you will have access to all of the toys. Load up Chapter 3, Stage 3: Home and make a small box. Hold the box above your head and press
to switch to the sniper rifle toy. Then, press
to drop the box on to your head and fire one shot at it. It should launch the box to the moon, or at least 30 meters, and unlock your trophy!