Jon briefly considered telling Carol the truth, that the world had been messed up by the stone, but he decided to keep the stone secret. He'd rather only himself and Karyn know about it. And even then, he realized that Karyn knowing about it was probably a bad idea. After all, if she hadn't known about it, then she wouldn't have turned everyone into what he thought were crossdressers (women wearing dresses and skirts, and men not).
So he feigned ignorance.
"I have no idea," Jon answered Carol. "One moment, everyone was normal, and then suddenly men were wearing women's clothes and women were wearing men's. It's so weird seeing girls in dresses and skirts. It's just so wrong, ya know?"
"Yeah, I do," Carol said, nodding. "So, are we the only ones not affected? I mean, I know my friends Nicole and Sarah, and Sarah's boyfriend Jack haven't been changed, but what about anyone else?"