It has become a part of our Silicon Valley culture (at least) these days where people are quite courteous and sensitive when it comes to spoiling movies. Most people, from critics to random people, will almost always give a disclaimer when discussing a part of a movie that gives away some significant portion of the plot. Usually, a prominently typed or formatted, "SPOILERS," acts as the writer/talker's sufficient warning that releases them from any culpability for ruining someone else's movie watching experience. If this is ignored or forgotten, there will almost always be a socially justified strong reaction out of the reader/hearer to berate the spoiler-er.
With DVR's found in more and more households, it seems (definitely for me) that watching sporting events on tape delay is becoming more and more and commonplace. If you've ever attempted to watch a game on tape delay, you know that there are definitely pros and cons. Pros include being able to skip commercials and watch the game at your own pace. With a growing family and a marriage that is a top priority, the less time I can spend in order to get my sporting fix means the more quality time I can give the wifey. However, the cons are where it really becomes an adventure.
Especially if the sporting event is fairly high profile, like say a play-off or finals game or a top college football game, and most people know you're a fan, you might as well turn off your phone. Even if you try not to look at your text messages, based on the timing and possibly who sent it to you (on the home screen), you usually can figure out if it's positive or negative. Status messages (on GChat, Facebook, AIM, etc) should also obviously be avoided.
There are also always people who want to talk about the game and inevitably, in passing you're also likely to find out about the game - people gathering around a TV and cheering or groaning, people who were following on the internet or on their phone, etc.
Of course, I acknowledge that if one chooses to watch a game on tape delay, you can't complain *too* much if it gets spoiled, especially if you were in public places during the game. But really, it always feels like a gut-punch especially if I had been building up the watching experience expectation in my mind for a while - to just kick back with a glass of scotch and just chill. So as a result, I'm proposing, out of the goodness of peoples' hearts, that we institute a, "SPOILERS," cultural shift that, like movies, encourages a sensitivity to people's sport watching preferences.