The Safer Stone: Accident

"Jon, put some clothes on!" his mother yelled from the living room. His little brother Mikey giggled at Jon's nakedness. "Mikey, please," she said. Jon immediately ran back upstairs, but in doing so, he accidentally stepped on the tack that he purposely avoided on his way down. The pain was excruciating. And in a fit of panic to make the pain go away, he made a wish, forgetting that the stone would force him to either set a time limit or a reversal condition. "I wish ..."