"I get it!" yelled Jon.
"What?" replied Karyn. "You got what?"
"I figured out the loophole. Look, Karyn, when I came in here I still knew who you were. But the stone changes reality so it's normal for you to be a couch, right? If I remember you being Karyn, the reality change couldn't be that you were always a couch. The reality change must be that you were Karyn--so I could know who you are--and something changed you into a couch just now. All I need to do is figure out what that was, and depending on what it was, I might be able to reverse it."
"I don't think that's going to be so easy," said Karyn.
"Sure it is. I wish I knew what in this reality turned Karyn into a couch just now."
Jon grimaced as the explanation came to him. "Oh, come on, that's ridiculous. But I guess it makes sense. Maybe I can figure out a way to turn you back now."
"But what was it?" asked Karyn.
"Oh," said Jon, "it's...."