First ask for four volunteers and tell them that they are going to be decieved. Ask each volunteer who they think that they can win, to distract them from the fact they are going to be decieved. Tell them to kneel around the baking sheet. Tell them ypu are dropping candy and whomever gets it the fastest gets to keep it, but they have to keep their eyes on the baking sheet. Drop a piece of candy, they should all go for it. Drop another, and another. Drop them until they understand the game. Then when they are comfortable and know whats going on, drop the egg or water balloon. They should all go for it and get messy, or wet. Tell them they can clean up. Point out that even though you warned them something bad would happen, they were conditioned to grab. You can liken this to how bad habits or mistakes can become sins because we’re conditioned to act a certain way.