Jon waited for a few minutes, but nothing happened. At least, nothing that he would describe as being "interesting", so he just went about his night finishing his homework, watching some TV, then going to bed.
But what he didn't know was that his wish did do something interesting. It's just that the right circumstances hadn't happened yet.
Any lie (even a sarcastic remark) that was made in Jon's presence (within earshot of him, in other words) would be turned into a truth and reality would change accordingly. But this only affected other people and not Jon. He could lie as much as he wanted, but none of his lies would change reality.
Of course, since this all would happen because of a wish he made, Jon's memories wouldn't change to fit every new reality, since he heard his own wish. But as to whether or not the memories of the person who lied changed ...
(well, that's up to the author)
