Hm. I can't imagine where I've seen this before.
Anyway, fanfiction writers- sit up and take notice. Still trying to get a grasp on that elusive lightning in a bottle that really makes a story worth reading? You might want to try giving this a shot. Mister-Hand sends this to us in hopes that it can help you guys like it's helped some of the writers over on DeviantArt. In it, the second-best pony walks- er, trots you through some of the very basics of writing compelling works of fiction. Kurt Vonnegut abound!
Click the picture, or follow this word to read the whole comic.