The hell?!

This was the most bizarre trap in the history of Hogwarts. There was no way Peeves could have concocted it, or a Hogwarts student, without getting expelled first. Perhaps they'd accidentally sat above some exercise for the NEWT DADA students?

Seneca winced, a reaction caused by both Frida's squeals and the further dirt that had dropped on them. She raised her wand and cast: "Finite incantatem!" And the dirt stopped dropping.