If you are going to DVR a show, event, or game for later viewing....
You must take some measures and responsibility to prevent it from being ruined for you.
Avoid the internet. That's it. Don't be surprised if the results of the televised end up on a strictly news website. If you are going to be online you may have the surprised ruined for you. People my post the results on other social media (facebook, twitter, etc)
Avoid your cellphone. In order to prevent someone from texting you a "OMG did you see that......", just turn off your phone until you watch the prerecorded event.
Don't walk your dog and run the risk of your neighbor screaming at you "OMG did you see that...."
If you are going to record an event that most of the world is going to observe live, you bear some responsibility for your later viewing pleasure.
On the other hand you cannot watch a movie in the theater on it's opening weekend and post on the internet "OMG Vader is Luke's father" when the rest of the world has not had the opportunity to see the movie in theaters yet. There is a 2 month window on movie spoilers.
If you live on the east coast and people on the west coast have not had the opportunity to see a show or event, YOU MUST POST A SPOILER ALERT, or don't say anything at all about the event. Titles like "Season Finale of Dexter Spolier Alert" are ok while "Family Guy kills off Brian, Spoiler Alert" are not ok.
Holy shit I want a sandwich, anybody else?
= new reply since forum marked as read
Even though I don't really get into any of those things, I am still pissed at the friend who spoiled the Luke's father moment for me
The ONLY time it's OK to put spoilers in a subject line is if it's actual real news.
I actually turned my laptop off until the end of Breaking Bad. I was incommunicado that night. 
