Imagine learning that Darth Vader was really Luke Skywalker's father before you had the chance to see The Empire Strikes Back.
Prematurely revealing the ending, or a major plot twist, of a film, television show, or book is perhaps the biggest crime in pop culture etiquette. Before the birth of social media and the omnipresence of the internet, staying away from spoilers was relatively easy. But in today's social media age, with continuous, free-flowing and free-roaming information, staying away from unwanted information has become extremely difficult.
While there are people who spoil endings on the internet for fun (known as "trolls") most spoilers on social media are the result of an honest mistake: people eager to discuss a film or book they have just finished.
Spoiler etiquette - meaning where and, more importantly, when to discuss sensitive information - has been well established among diehard fans, but is still a grey area for most others.
Even professionals get it wrong.
Respected film trade publication The Hollywood Reporter angered a legion of fanboys last month by publishing a story on the death of Peter Parker (aka Spider-Man) in the 700th issue of The Amazing Spider-Man comic book at 9.57am on the day of the book's publication.
"Really, guys? You realise this issue went on sale today and you're publishing an article with a spoiler in the title at 9.57am," wrote one angry commenter. It was the most liked comment on the webpage.
To make matters worse, The Hollywood Reporter sent out a tweet about Parker's fate, to its 457,000 plus followers, shortly after 10am.
"Publishing a piece with a spoiler in the headline was bad enough, but tweeting it was even worse," says Cyrus Lo Sai-man, entertainment editor at TVB.com "If you saw it on the website, you at least had to actively go on their publication, but on Twitter, you could be minding your own business and come across the information."
Twitter, because of its openness and opinion-sharing nature, is a breeding ground for spoilers.
Industry insiders and pop culture fans Ross Chen, founder of LoveHKFilm.com and Mark Hughes, Hollywood scriptwriter and film critic, say they stay off Twitter during "crucial spoiler times".
"I stay off Twitter when there's potential to be spoilers, like when The Dark Knight Rises came out," says Chen. "And if I ever see anyone tweet a spoiler, I 'unfollow' them [on Twitter]."
Hughes says while Twitter trolls are looking for attention, the media should know better, but sometimes spoil details on purpose to elicit a reaction.
He says there's a mentality in the new media to get people to click on to stories by any means necessary. "That's why they put a major spoiler in the headline."
The only way to fix the problem is to educate casual fans on spoiler etiquette, says TVB's Lo.
"I think the problem is worse in Hong Kong because analysing and discussing pop culture isn't taken as seriously here as it is in the US," he says. "There isn't even a Cantonese equivalent of the term 'spoiler'.
"Look at TVB shows - they practically give away the ending or major plot points of the series in the opening credits in their montage of scenes."
Web-savvy individuals should already be familiar with the first rule of spoiler etiquette: start your sentence with "SPOILER ALERT", in caps, followed by several spaces (or preferably starting a new paragraph), before continuing with the sensitive material.
That basic rule was established when the internet was still mostly forums or blogs. More sophisticated rules need to be established for today's real-time, free-flowing information outlets like Twitter or Facebook.
Last year, a group of actors from hit US television shows gathered together for an "Official Spoiler Rules" web video on popular website CollegeHumor.com In it, Julie Benz, who plays Rita Bennett on the hit television series Dexter, pleads with fans to be considerate when discussing plot points, adding: "In the age of DVR [digital video recorder] and internet, not everybody is watching television at the same time."
Nelsan Ellis, who plays Lafayette Reynolds on True Blood, says fans should wait two weeks after an episode, two months after a season finale, and a full year before a series finale before discussing the ending openly.
But sometimes a plot point in a film or television show can be so bad that even the most considerate fans break spoiler rules.
Garron Kertnen Chiu, digital marketer by day and television watcher by night, says the time of the finale of ABC television series Lost was infuriating, as "everyone on Facebook and Twitter just vented at once".
Chen of LoveHKFilm.com had a similar moment. He says the twist in the 2009 Hong Kong film Murderer, starring Aaron Kwok Fu-shing, was so ridiculous that he couldn't write the review without mentioning it - albeit vaguely.
"I didn't actually tell people what exactly the twist was," Chen says. "But by letting them know that it existed, I did perhaps spoil part of the experience."
But is spoiling something terrible a bad thing?
"That should be a rule - it's only a spoiler if the show or movie is any good," says Lo, laughing. "That Aaron Kwok movie was so bad all of Hong Kong talked about it. That's not spoiling - that's a warning."