"No I'm not," said Rosa, making a face at this moose-boy, and then deciding that a face wasn't enough, she was going to stick her tongue out at him, too, because he pretty much deserved it. "You can't infect me, I'm cootie-proof, but nice try."

Another pause, a moment of decision.

"Sweetheart."

There. If he was going to call her that, then she'd just call it to him back, see how he liked it.