" And then he heard Mad-Eye Moody’s voice, echoing in some distant chamber of his empty brain: Jump onto the desk . . . jump onto the desk. . . .
Harry bent his knees obediently, preparing to spring.
Jump onto the desk. . . .
Why, though? Another voice had awoken in the back of his brain.
Stupid thing to do, really, said the voice.
Jump onto the desk. . . .
No, I don’t think I will, thanks, said the other voice, a little more firmly . . . no, I don’t really want to . . .
Jump! NOW!
The next thing Harry felt was considerable pain. He had both jumped and tried to prevent himself from jumping — the result was that he’d smashed headlong into the desk, knocking it over, and, by the feeling in his legs, fractured both his kneecaps. "

― J.K. Rowling , Harry Potter and the Goblet of Fire (Harry Potter, #4)