When Game of Thrones entered its sixth season in 2016, it was true spoiler territory for those of us who had read the GRRM books before HBO's TV adaptation turned the property into a worldwide phenomenon. Due to the author's glacial writing pace, at this point the TV series went past the point that the novels had reached. Thus nobody -- book readers or tv viewers -- knew what events would unfold in the story. I usually don't watch the episodes until a few days after they air. On the day the first episode aired I found while scrolling through my social media feeds that one of my friends (who shall remain nameless) posted what turned out to be the resolution to the cliffhanger ending of both the previous TV season and the last available book. It was of course followed by immediate comments of "Spoiler!" from me and a few other people.
Some people might say, what's the big deal? When you're invested in a story, getting unintentionally spoiled as to future plot points is a terrible feeling. It robs of you of the the experience, as you now go into the story with certain expectations. You only ever get one chance to watch/read/experience a story for the first time. If you enjoyed that experience, you should be considerate of others and not take that same experience away from them. (Unless they ask for it of course.) Sure, it's just a story. But hey, life is stories.
The need to talk about what happened in a story is certainly understandable. You're excited about the story and you can't wait to talk to people about it and tell them what you think and speculate about what happens next and so on. It's akin to coming back to school/work on Monday and discussing what happened in your favorite TV shows over the weekend. (Back in high school we probably had multiple Monday morning conversations along the lines of "Can you believe Goku is still running down the snake road?")
And when it's you and your buddies talking about it over the water cooler after everybody's seen the episode in question that's fine. But in the modern age, we have social media, and with social media comes the tendency to broadcast your thoughts to the world. If you're not careful you're going to accidentally spoil everyone.
I'm writing about this because of Avengers Infinity War of course. I normally post a spoiler-free review on Facebook after watching a movie, but there's so much to unpack in this movie I had to get down my thoughts and write a spoiler-filled review over on NedStarkDies.com. Marvel themselves were well aware of the dangers spoilers poised in ruining people's experience of the movie. In the weeks running up to the movie, they ran a campaign to encourage people to avoid spreading spoilers using the hashtag #ThanosDemandsYourSilence. The campaign included a letter from the Russo brothers and a video message from the cast. The campaign seems to have been largely successful, which is amazing to me.
Side note: I wasn't able to watch the movie on the opening day, so it was a bit brave for me to still be scanning my feeds in the days before I was able to watch. But I think I got away mostly unscathed. I will say however, that I do consider as mild spoilers reactions like "I need a hug" or "that wasn't good for kids". I mean, that already implies the tone of the ending. But then again, I'm probably more finicky about spoilers than most -- these days I tend to avoid all but the first trailer for any movies I plan to watch since I feel that succeeding trailers already tend to spoil too much.
One last spoiler-related anecdote: my brothers and I are big fans of profession wrestling (WWE). We used to follow all the storylines and whatnot. Back in 2005, up-and-comer Dave Batista (who also happens to appear in Infinity War) got his first title shot at Wrestlemania 21. One of my brothers was unable to watch the show at the time that it aired on local TV. But he didn't want us to spoil the match outcome for him until he got a chance to find a copy that he could watch. We didn't want to download it because it would have taken too long on our very slow internet back then. It took him a couple of months to find a store that had DVD copies of the event. As the lady behind the counter handed him the DVD she commented something along the lines of "Batista was so good in this event sir, he became the champion!"