"I wish that Jon won't wake up while I'm in here tonight."
Fortunately, this wish worked, since it named Jon--it doesn't matter who made the wish, it would do almost the same thing. The only difference was that Jon would stay asleep while Jon is in the room tonight. So he couldn't wake up when Zoe leaves, but he would wake up in the morning (since it's no longer night).
Then Zoe tried a test. "I wish that a dollar bill would appear in front of me."
The dollar bill appeared in front of Jon, but Jon was sleeping and his face was pointed in Zoe's direction, so it happened to be in front of Zoe anyway.
Zoe, satisfied that the stone was working, decided to make a real wish....
