Dante forgot to include levels of Hell specifically reserved for those who - for whatever the reason - have much to answer for in blurting out what happens inna flick before you've seen it.
Or, as you're entering the theatre - as with "Robin and Marian" - when an associate pulled us aside and said, "By the way, you DO know ________ ______".
NO, WE DIDN'T, IDIOSO, THANX TO YOUR 'SURPRISE' REVELATION!!!
But the REEEEEL Rosetta Stone of Stupidity in this regard was during the original release for 1968's "Planet of the Apes".
The next audience was waiting outside to be let in (us among 'em) when the nitwit ushers let us all in JUST AT THE PAY-OFF ON THE BEACH SCENE!!!!!
Where the holy hell was Edward Woodward when we really needed him?!?
Yeah. That picture caused quite a stir. The saving grace for having seen it in its theatrical run like POTA is that a well-executed build helps soften the spoil. Not always, of course. I'm thinking of Witness For The Prosecution, e.g. And I despise folks who take pride in having called Serling or Shyamalan parting shots early. Hell we could all do that if we wanted but it's more fun choosing to refrain and getting into it and milking the build-up instead.