' "Sir ‑ I got a Ministry of Magic leaflet by owl, about security measures we should all take against the Death Eaters . . ."
"Yes, I received one myself," said Dumbledore, still smiling.
"Did you find it useful?"
"No, I thought not. You have not asked me, for instance, what is my favourite flavour of jam, to check that I am indeed Professor Dumbledore, and not an imposter."
"I didn't . . ." Harry began, not entirely sure whether he was being reprimanded or not.
"For future reference, Harry, it is raspberry . . . although of course, if I were a Death Eater, I would have been sure to research my own jam-preferences before impersonating myself."
Harry Potter and the Half-Blood Prince
I don't think there's any need for me to wax lyrical about my undying love for Harry Potter so i'm just going to brood over having only one book left after well over a decade of making it last as long as possible.