The writer (professional or otherwise) has stuck in a cameo, done something particularly egregious in some sense or another (ex: stood up on a soap box to pontificate and so on and you so don't agree with them, written something horrifyingly sexist or whatever. or something you agree with for that matter. ) inserted someone or the name of someone they know (ex: certain Baen writers insert and kill off a character named after a fan). This would be the place to share your amusement/flailing/exasperation. My first offering: So, Stirling's new Change book came out, Prince of Outcasts. And I'm innocently reading along as you do, and see that someone is from a place called "Hali." Which at first did not register. Until the character quoted from The King in Yellow. Which is a mysterious play that causes people to go mad for various supernatural reasons, and is a concept creation of Robert W Chambers, who also made The King in Yellow the title of a story collection. The character also mentions needing a "repairer of reputations" which is ALSO a name of one of the stories in the collection. (Character is/was super bitter because his dad was a traitor.) It was bad enough that in a previous book in the series, there was a weapon shop operated by a guy named Isher. (The Weapon Shops of Isher is the name of a science fiction book by A.E. van Vogt ) But here we have what is definitely a major plot point, apparently based off of Chambers King in Yellow, and it's like Chekov's frigging gun is actually a Sherlock Holmes story that's been incorporated in the plot. (I should totally not be this amused/exasperated, since I have a tendency to put shout-outs and cameos in my fanfiction, but STILL. I SEE WHUT U DID THAR STIRLING. )
I just saw a picture on Tumblr of Idris Elba dressed up on that Dark Tower set. So I'm just going to say "The Dark Tower" and leave it at that.
Oh, I don't know if this counts, but I refuse to believe Brandon Sanderson's insistence that the fact that he made a magic system where wearing an aluminum foil hat blocks mind control was an accident.
