Sadly Mogget doesn't watch American high school movies so the phrasing flies over his head. He doesn't move from his seat. He is firmly parked in the seat.

"You won't be going anywhere if she thinks you're using another witch to spy on her."

His eyes challenge Cesare to deny it. Lydia isn't the brightest, but that could make it easier to get information out of her or even to turn her against Samantha if Cesare so chose.