"That's all right, pay no attention to me, just make yourself at home," I tell the self-propelled whoopee cushion, then audit the itemized receipt with a sinking heart. Judging from the bottom line, cats fall somewhere between a new Porsche and a used Lamborghini in running costs, and I've got a nasty suspicion that I'm not going to be able to expense this claim. I mean, I might be able to concoct an experimental protocol that involves hosting one all-black specimen of Felis catus in the lap of luxury before sacrificing it on a summoning grid--but I suspect that would annoy Trish, and one should always avoid pissing off the departmental secretary."