The stone was a body swap stone.
The stone swapped bodies, not minds.
For example, if Jon went to a pep rally and Sarah was cheerleading at the rally and Jon made a wish, the wish would be granted, swapping Jon and Sarah. Jon would be where he was when he made the wish but in Sarah's body, with his clothes resized to fit Sarah's body. Sarah would still be cheerleading but in Jon's body, with her cheerleading uniform resized to fit Jon's body. She would be unaware of the swap, but Jon would know.
