"Kids are not as smart as parents!"-Toothpaste
I would like to invent a toothpaste that is flavorable yet cleans your teeth. The deal is this toothpaste will turn a kids teeth brown if he/she smokes a cigarrette, turns green if he/she smokes marajuana, and turns bright yellow if he/she drinks. This would embarrass a teen so much that he/she would not think about doing any of those mentioned above again. The teen wouldn't know what made his/her teeth turn the colors and the only way to get the original color back was to brush his/her teeth with the same named toothpaste but not the kind with the ingredients that make the teeth change colors. Parents would know what their teens were doing behind their back.
Reward: If anyone shall use this product and sell it I would like to get 2 tubes a year for the rest of my life for free.