Spoiler alert: This article contains unflattering commentary about The Cabin in the Woods. And maybe a vague spoiler or two.

It has long been considered common courtesy to refrain from ruining surprises: Gift-shaking is strictly for impetuous children; only the hopelessly uncouth will give away the punchline before the joke is over. And anyone who dares to update his Facebook status with details about who died on Dexter or which American Idol contestant was eliminated before fellow fans have had a chance to watch is Public Enemy Number One.

A few years ago, Anni Bruno took to her Facebook wall in anticipation of the season finale of a Doctor Who spin-off that she loved, planning to invite some friends over to watch with her -- one day after the show had first aired in the U.S. A girl immediately posted which characters lived and which ones died, Anni said. I think she thought she was being funny.

But Anni was anything but amused. I was shocked, hurt and angry, she said. I felt that any trust we had was totally betrayed. I immediately de-friended her on Facebook, then set my status to indicate that anyone that cruelly spouts out spoilers like that will be officially dead to me.

Despite the offender's attempts to initiate contact, the two women have not spoken again. I had been waiting for that show to air for something like two years, Anni explained in an email. She ruined the ending. And with it, the friendship.

Decades ago, morning-after water cooler chat about a favorite program was a natural extension of the viewing experience (i.e., Who Killed J.R.?) But as more and more people consume popular television days, weeks, months and even years after a program's scheduled air date -- thanks to the widespread use of DVRs and digital streaming -- the only socially acceptable reaction to a dramatic plot twist, a solved crime or a surprise ending is to keep your mouth shut -- and your social media feeds free of the dreaded spoiler.

There's a venue for discussions and community around any show or film. Your Facebook wall is not the place to give anything away, said Jamie Dwyer, a creative consultant who DVRs his favorite shows and makes an effort to watch important episodes within a week of the original air date.

Entertainment isn't life or death, though, Jamie continued. With social media as integrated into our lives and popular culture as it is, you can't hold too much of a grudge against those who ruin everything with their idiocy and lack of care for you as a person.

And it might not be fair to exile a friend for spoiling a plot point after a reasonable amount of time has passed. But those interviewed for this story -- urban professionals ranging in age from their late 20s through their early 40s -- had varied opinions on the length of the spoiler moratorium.

I wouldn't expect other people to protect me by avoiding spoilers about a show on Facebook for longer than two to three days, max, said Marisa Bowe, who made a public plea on her Facebook wall for fellow Mad Men fans to keep their spoilers to themselves on the night of the much-anticipated season five premiere. I think it's both asking too much and unrealistic to expect more.

After that, she said, it's the responsibility of the person who hasn't seen the show to shield their eyes.

While Jamie Dwyer believes it's pretty much never okay to reveal major plot points on social media, he agrees with Marisa about the responsibilities of the spoiler-phobic.

If you're going to hold out ... you pretty much need to commit to being okay if something is revealed before you watch -- and you have to have some due diligence online or talking with others, Jamie said. I've never watched 'Mad Men.' I plan on it one day. So, I steer away from headlines or discussions that may reveal current story lines.

Chris Fairbanks of Brooklyn thinks spoiler rules are specific to the type of program being spoiled. Viewers should wait at least a week before revealing the results of reality competition shows on social media. With scripted television shows, I don't think it's acceptable to discuss it publicly in social forums where you don't know who's seen it or not, even well after the fact.

Rebecca Cohen will often watch a favorite show during its scheduled air time -- but since she lives on the West Coast, she risks having an episode spoiled for her by social media updates from the East Coast.

It sucks to check Twitter and the trending topic is 'RIP Shane' and you're on your way home to watch that episode, she said. I'm realistic, so I know not to look at Twitter when my favorite shows are on if I'm not watching.

Immediate postmortem chatter on social media is so prevalent that I can't even call it bad etiquette, Rebecca said It's just the way things are.

Those who make and break the rules of spoiler etiquette are largely concerned with episodic television, which demands hours of viewing and often years of investment from its audiences. But every now and again a feature film will enter the spoiler culture fray.

Take The Cabin in the Woods. Directed by Drew Goddard and co-written by Goddard and Joss Whedon, who enjoys a dedicated cult following as the creator of Buffy the Vampire Slayer, the so-called horror film arrived in theaters in April with what the New York Observer's Rex Reed called a preordained sort of word-of-mouth anticipation.

The Cabin in the Woods premiered more than two years ago at SXSW 2010. At the festival premiere, Whedon introduced the film with a request to keep plot points under wraps. I hope you enjoy it, and then sorta keep it to yourself, he told the audience. In other words, no spoilers.

In a subsequent interview with SFX, Whedon raised the stakes -- handing would-be blabbermouths a good-natured threat.

If you give away the plot of this film to someone who hasn't seen it, he warned, I will personally come to your house and make fun of you in front of people that you respect.

Whedon is not the first (and surely not the last) filmmaker to make spoiler-related demands of his audience. Alfred Hitchcock gave strict instructions to theaters showing Psycho to ban latecomers from entering a show after it had begun. (This logic was to eliminate confusion among viewers who might arrive after Janet Leigh, the purported star of the film, is -- SPOILER ALERT! -- killed off in an early scene. There may or may not be a shower involved.) Newspaper ads for the movie reiterated Hitchcock's directive, and they requested that audiences remain tight-lipped about what they saw: After you see the film, please do not give away the ending. It's the only one we have.

Hitchcock and Whedon were undoubtedly aware of what happens when people refuse to talk about a movie they've seen: Other people go see it. The Cabin in the Woods opened at number three at the U.S. box office, grossing nearly $15 million on its opening weekend (which coincided with Friday the 13th of April, 2012).

The spoiler lockdown prompted acrobatic reviews from critics who delighted in navigating the verbal minefield. Forbes magazine's Carol Pinchefsky wrote her review as a Mad Lib: PERSONAL NOUN is VERB into the cellar. The others VERB. Unknowingly, they VERB NOUN, reads a synopsis of a critical scene.

In general, reviewers praised The Cabin in the Woods -- the movie has a 90% favorability rating on popular movie review website Rotten Tomatoes. A negative review (with a pretty unforgiveable spoiler) from the Village Voice and Reed's crusty critique were in the minority.

As the L Magazine's Henry Stewart pointed out, the longtime Observer critic got half of the basic plot points factually, objectively wrong. Reed may have intended to spoil surprises in The Cabin in the Woods, but it looks like he might have been too confused to effectively ruin it for anyone.

Though I thoroughly enjoyed the film, I confess that, like Reed, I was confused from time to time, despite my best efforts to stay with the program. Perhaps I am dull, or maybe I was too distracted waiting for a gasp-inducing, narrative-flipping surprise twist a la The Sixth Sense or The Usual Suspects'' -- one that never came.

Without a doubt, The Cabin in the Woods is a clever send-up of the horror genre. But I am not sure the gag order -- enforced as though it were punishable by death -- is fully merited. From the start, the film was marketed with the message that all is not what it seems: You think you know the story, reads a message on the movie poster, which includes additional visual cues about one of the central conceits. (Perhaps the poster should be updated to read You think you don't know the story.)

At the risk of unleashing the Whedon zombies upon myself, I feel a question must be asked about Cabin in the Woods: Wouldn't prohibiting fans and critics to talk about the movie in any meaningful, coherent way be a neat way of glossing over the absence of any meaningful, coherent plot?

The better a movie is, the more it is not relying on simply hiding stuff from the audience, said Professor Nicholas Christenfeld of University of California San Diego's Department of Psychology. 'No one says, 'No, no, no! Don't tell me whether Oedipus dies!'

Christenfeld co-authored a 2011 study that examined the impact of spoilers on the enjoyment of short fiction. The research yielded surprising results: The study subjects reported enhanced enjoyment of a story when a spoiler was given prior to reading it. (However, the spoilers were not announced as such; they were delivered implicitly by way of a preview synopsis that seamlessly incorporated a critical plot twist). Christenfeld and his colleagues are duplicating the same research on TV viewing.

Christenfeld admits that he went into the study expecting to find that spoilers actually spoiled the experience for the reader. And he concedes that he's met many people who discount his counterintuitive results.

There are lots of people who have told me they think the research is absolutely wrong; they don't believe it, he said. And I ask them: 'So, you have a favorite movie? Do you re-watch it with pleasure?' And they say, 'Of course I do!' And it gives them pause, but it's very hard to change people's minds -- despite further historical evidence that we are not hardwired to depend on the element of surprise.

In the old days, there was a tradition of retelling stories, he added. So there was an expectation that one knew the ending.

Although he stands by his research, Christenfeld is resigned to the fact that it will be very difficult to convince consumers of entertainment media not to fear the spoiler.

The very term 'spoiler' already has a presupposition about its effect, he said. It's not an 'end giveaway' alert, it's a spoiler alert, and that certainly has negative implications.