Spoiler alert: I once mentioned how Twin Peaks ended in a Radio Times article and got berated for it by readers.
In half a sentence, I had given away the answer to the entire series' big mystery of who killed Laura Palmer - and you have to agree that was a pretty big spoiler.
But in my defence, I wrote that 16 years after the show had finished. When does it become OK to talk about a TV show's plot twist?
Actors from US dramas, including The Walking Dead, The Wire and Battlestar Galactica, have prepared an answer. Once and for all, there are rules. Not only that, there are punishments for people who break them. Punishments that range from public shunning to mandatory knife fights*. This is serious stuff.
To tell you more would rather spoil it, so just watch Julie Benz from Dexter, Masi Oka from Heroes, Michael Trucco from Battlestar Galactica and Fairly Legal, plus many more, in The Spoiler Etiquette.
*we do not advocate knife fights...