It Was His Sled
A Twist Ending that used to be guarded carefully as a Spoiler, but thanks to Popcultural Osmosis, everyone within the target demographic knows the ending already, even those who haven't even seen the show. It's probably never going to surprise anyone again. In many cases, the twist becomes the central fact known even to those only noddingly familiar with the work, and other adaptations take it as read from the beginning.
Named after a line from Family Guy where Peter records the above quote over the best-known example of this trope, Orson Welles' film Citizen Kane.
Sometimes the work will be remade/adapted, and the ones responsible will know better. That's when they twist the twist itself, making it Not His Sled.
If this is the only thing people know about the work, it is All There Is to Know About "The Crying Game".
- Dragon Ball: Exactly what entailed being a Super Saiyan was a mystery at one point, but it's become such an iconic part of the series that you almost certainly know about it by now even if you're not a Dragon Ball fan.
- Harry Potter and the Half-Blood Prince: Famously a target of spoiler campaign by, ahem, pranksters; anyone who knows anything about Harry Potter these days knows that Snape kills Dumbledore.
- Citizen Kane: The Trope Namer.
- Star Wars: Everyone knows by now that Luke, I Am Your Father (although this is actually a misquote), but this was a well-kept secret (even kept a secret from the actors) prior to the release of The Empire Strikes Back.
- The Sixth Sense: Turns out, Malcolm was Dead All Along, but you know that. Everyone does.
Wait, wait... What Was Whose Sled?