"Boredom, someone dared them to, they were drunk and thought it sounded funny," Corrie says promptly - and a little too loudly: someone turns to shush her. She rolls her eyes and drops her voice again, leaning forward to compensate. "Psychology experiment about how quickly people accept whatever explanation they're given. Or about following instructions even if the person ordering you's an animal."

She shrugs. People do loads of things for loads of reasons. It's less clear to her why anyone's going along with it. "Maybe they're mind-controlling anyone who goes in to confess," she adds off-handedly.