The stone he put in its place looked almost exactly like Jon's stone, except that it wasn't. It was The Double Substitution Stone.
It worked just like the normal stone, except that after the wisher states his or her wish, two of the words of the wish are substituted by another two words, but two words that would still make some sense.
For example, if Jon said "I wish I was drinking a glass of milk," the stone would then grant it in a number of other random ways, like "I wish Zoe was throwing a glass of milk," or "I wish I was throwing a glass of water," or "I wish Mikey was drinking a glass of water." Of course, all of these examples are fairly harmless, but the stone could do a lot worse (like instead of water, the stone could replace the word "milk" with any kind of liquid, like blood or gasoline or even something disgusting like urine).
