"WAIT!" Karyn yelled. "Before you start wishing, you need to find out who the rock thinks you are."
"What do you mean?"
"Well, you could wish that Jon was 4' tall, but do you really know who that wish would affect? You feel like Jon, but Jon made a wish to be his mom."
"I guess you're right," he replied. "Something small, then... I wish Jon would sneeze, and Rachel would cough, in five seconds."
They waited for a few moments, Karyn watching "Jon" intently. When the time came, "Jon" felt a pressure in his chest and coughed lightly, and they heard a sneeze from downstairs.
"Well, that settles it. Guess I really am my mom."