Jersey's head turned a full 180 degrees as he looked at who had come into the room. Casimir was a bit surprised to see someone actually have the fortitude to walk in here.... unless it was going to be some sort of prank. If it was a prank, then Casimir would show the planners the terror that were his spells. 
Really though, the guy that just came in didn't look suspicious. He also bore a slytherin emblem, obviously telling he was from the same house as he was.

"I'm Casimir. Nice meeting you," he said simply.