(I liked the concept set up by whatever, but I wanted to increase the possible options. So here goes.)
After arriving at school, Jon went to drop off a few things at his locker. Making sure that his actions went unobserved, he reached behind his books and pulled them forward a few inches, creating a hidden space. Then, he surreptitiously transferred the box containing the wishing stone to the makeshift compartment and covered it with his gym clothes.
Satisfied that he had taken every possible precaution, he headed off to class.
Normally, Jon's assumption that things were relatively safe would have been correct. Unfortunately, since he now had the Proximity Stone, he had inadvertently made his locker into the epicenter of a much larger hazard. An invisible bubble, forty feet in diameter, now stretched across the hall and even into adjacent classrooms. Anyone within its boundary, if they uttered a wish, could accidentally change reality for the entire town!
In only a few minutes after Jon had gone on to class, numerous students passed through the fateful boundary as they shuffled on to their morning classes. All too soon, one would speak the words "I wish," and the day's peace would be shattered.
