The fridge is one of the most excruciating things to clean, so it makes the perfect target on April Fool's Day. For this prank, just fill up a water balloon with whatever you want, lay it softly in one of the shelves on the door, and close the door with the untied end of the balloon stretched out so that the door will close and seal it. When your victim opens the fridge, it'll explode all over them. Simple and effective. Watch to see exactly how it works.