Ok, so this isn't an actual quote from HP, but it's a troll/meme of something someone picked up...
Quirrel: "TROLL! In the Dungeon!"
Dumbledore: "Everyone to your dormitories!"
Slytherins: "Our dormitories are in the dungeons..."
Good job, J.K.R. Good job.
And then there's always this one...
Ron: Why spiders? Why couldn't it be "follow the butterflies"?