At that very moment Jon and Karyn where using the stone.
"So Karyn I've narrowed it down to ether Biff or Sara" Jon said
"Ok Biff, No Sara. Waite I've got it let's do a swap to them" Karyn said.
"Swap what?" Jon asked
"I don't know ether like their hair, or their chests!" Karyn said.
Jon started laughing hysterically. "Biff with Sara's Big breasts. But you know what would make it even better if we swapped even more than that."
"Okay, like what?," Karyn asked.
"like their hair, chests, and some other random things like their shoe choices and favorite color" Jon said as he picked up the stone "I wish that Biff Meadows and Sara McMillan would swap their chest, hair, shoes and favorite color, until I wish otherwise."
Biff was compelled to look at his pocket watch as reality shifted.
