Jon was back at home wondering what sort of wish he might make that would be very valuable yet not be flagrantly disruptive. He didn’t want to force anything on anyone else, yet didn’t want to encumber himself potentially permanently. It therefore needed to be a wish that would be applied to himself yet also could be turned on and off. If for instance he wished for a certain ability that he could switch on and off at will, it would not be undoing a wish for him to simply turn it off but rather simply exercising one aspect of the ability he asked for.
So what would this ability be? The ability to alter his body? Maybe later. Some cliché superpower like super strength or speed or flight? Nah. Invisibility? Another thing to consider later but he frankly was just not in the mood. And then he got the perfect idea.
Jon held up the stone and said “I wish to be able to see the thoughts of others, that would appear in front of them like subtitles in a movie, but for this to be something I can turn on and off as many times as I want, and that I would turn them on by saying subtitles on, and I would turn them off by saying subtitles off.”
He put down the stone. “There. Since I can turn them on and off, there’s no way this could really be a problem. All right. Here goes. Subtitles on.”
Jon thought it was a pity that no one else was home yet to test this with. His mom wasn’t going to be getting there for another half hour. He figured he would wait.
Little did he know, the rest of the world was now in chaos, because everyone the world over suddenly found that subtitles appeared in front of them for every thought they had. After all, Jon wished to be able to see subtitles for everyone else’s thoughts when he switched on his ability, but he hadn’t wished for the subtitles to actually be intangible or visible only to him. For everyone else on Earth, actual tangible words floating in midair started appearing in front of them for anyone else to read their every thought. The thoughts of everyone other than Jon were now subtitled.