Random
Source Code
Random
The time at which it is deemed acceptable for a movie/TV show plot to be discussed in your group of friends without being worried about ruining it for others, because fans of the film/episode would have watched it as soon as they were able to.
Movies - 1 week. Fans of the film would be able to attend a screening within one week of the films release.
TV shows - 1 day. The true lovers of this show will live stream it or record/TiVo the episode and watch it as soon as possible.
"Dude, why are you so mad that I talked about who died in Game of Thrones this week? The show aired on Wednesday and it's Saturday. Spoiler etiquette has been upheld!"
An acknowledgment of a spoiler very much like a spoiler alert except that it's provided after rather than before the spoiler in question. See, for example, the Dinosaur Comics strip for April 15, 2011.
By extension, any would-be warning preceded by the thing it's supposed to warn against.
"So then Snape kills Dumbledore. That's a particularly infamous spoiler." "Nice postfix spoiler alert, you numskull." / A week after the drop deadline, the registrar told me I was taking the wrong classes and wouldn't be able to graduate till next semester. Talk about a postfix spoiler alert! Does he think I'm Merlin or something?