The Unfortunate Event
Also known as The Unhappy Event.
When reviewing the film Harry Potter And The Half-Blood Prince, in order not to provide a spoiler into one of the major plot points of the film, it was referred to as The Unfortunate Event. This was because the week before, while "nurdling" (ie filling in some time before a race from Newmarket), Simon had massively revealed the end of the book, resulting in much listener anguish (though Simon insisted that there would not be a single person seeing the film who did not already know what was going to happen).
Henceforth, other similar situations where a major character dies unexpectedly have been referred to as this.
Having been suitably chastised, when it came to reviewing Harry On Camping, the Good Doctors continued to try to avoid giving away the precise nature of the Unfortunate Event as they described the set-up to the story. This was then gloriously undermined when the clip was played, in which Harry, Hermione and Ron discuss what Dumbledore had left them in his will - thus revealing that the great wizarding headmaster is now very dead. Oh well.
The events leading up to the Unhappy Event as portrayed in the film became the subject of some national discussion after Simon raised his concerns about them during Mark's review. The key is what happens to Harry. In the source book, Harry - under an invisibility cloak - is under a spell and so cannot move to prevent the Unhappy Event from happening. In the film, however, he does not act because he is told not to by Professor Snape - having previously been told by Dumbledore that he must trust Snape. Simon felt that regardless, Harry would have acted. This then became a conversation not just about an important change from the source material but a discussion about faith and free will, and ultimately how Harry' guilt might power the rest of the films.