[Question] Good HPMoR scenes /​ passages?

I’m doing a reading of good fan-fiction at a con this weekend, to counter the many “bad fanfic reading” panels. I want to read an interesting passage from HPMoR, but I can’t remember any particular passage myself, and I don’t want to re-read the whole thing this week. Can anyone remember any scene or passage that stuck in their mind as impressive?

It should:

  • be less than 1000 words

  • be understandable to someone who’s read Harry Potter, but not HPMoR, with at most one or two sentences of background info (please write those sentences in your reply)

  • be good at the things that make HPMoR special, e.g.,

    • a clever “exploit” of Muggle society using magic

    • gobsmacking you with a new way of looking at something you thought you knew well

    • convincing you that something that seems evil is the right thing to do

    • Quirrell or Harry creeping you out, scaring you, or making you question your ethics by being ruthlessly rational