My brother didn't like mushrooms. He was about six, and I was four years his senior. This posed a dilemma, as we frequently had pilze on our family dinner table. So I told him a lie.
"They'll give you hair on your chest." He looked skeptical. "Look, under the edge. See all those hairs under there? That stuff makes the hair grow." Now, ever since my brother could understand human speech, I had been working hard to help him develop a healthy imagination. We played a lot of make-believe, supplemented with a good dose of disinformation. With my explanation, his look of consternation transformed into one of wonder. He ate one, and then another, soon consuming all the mushrooms on his plate.
Twelve years later, my brother took me to task. Apparently he hadn't sprung a single dark hair from his chest region. Neither had I...must be a family trait. "Remember when you told me mushrooms would put hair on my chest? You were a mean brother. I actually believed you until Dad told me it wasn't true." Ah, foiled again. Seems my brother becomes more and more convinced, as we both enter adulthood, that I was quite cruel. It was all for his own good, really. Well, except for that time I assured him it was perfectly safe to jump off the second floor onto the trampoline...but that's another story.