‘How can you kill ghosts?’ ‘How should I know? The question doesn't usually arise!’ ‘You exorcise them, I think.’ ‘What? Jumpin' up and down, runnin' on the spot, that kind of thing?’ The Dean had been ready for this. ‘It's spelled with an "O", Archchancellor. I don't think one is expected to subject them to, er, physical exertion.’ ‘Should think not, man. We don't want a lot of healthy ghosts buzzin' around.’

— Reaper Man by Terry Pratchett (Discworld) (Page 159)