Jon knew that Zoe and her friends had often been teased by the popular crowd (which Sarah seemed to now no longer be a part of), so he made up a story that to him seemed plausible.
"I was trying to get away from Steve and Biff. They were teasing me again," Jon explained.
But it apparently wasn't a good explanation. And from the way Sarah reacted to it, it seemed as though Steve (Farber) and Biff (Meadows) weren't who he remembered them to be.
"Steve and Biff?" Sarah asked, sounding confused. "You got teased by a couple of dorks?"
"Dorks?" Jon asked.
"Yeah, they're nerds, remember?"