"Very good, Jane. Now, you better get to Karyn's house. She's waiting for you."
Jane smiled. "Yes, Mistress Sarah."
Because no one but Sarah and Jon heard her wish, reality had changed so that everyone remembered Jon as Joan, a slutty bimbo that was friends with Sarah McMillan.
So, when Joan showed up at Karyn's house, Karyn reacted to Joan as if she were the air-headed slut that Karyn knew she was. She didn't remember anything about the stone or the changes in reality because of it (like her bigger breasts and blonde hair, which she thought was normal for her).
Karyn opened the door, seeing the sexy, but slutty, Joan. "What are you doing here?"