Severus didn't blink. His eyes flickered down to where the man had hit his desk, lingered a moment, and then found his face again. "Ah," he said, allowing himself a small smile. "You think I'm joking. I can have the elves clean your quarters out for you, if you require convincing. You will be out of the castle by tomorrow, so that I can begin hunting for someone who can teach Transfiguration. - Do you understand?"