We've all become accustomed to seeing this warning, usually in a movie review. It means stop reading if you don't want to know what happens!
We've seen it a lot over the past week with Olympic coverage. Because of the time difference with London, NBC is showing events in primetime well after they've occurred.
I just cracked up this weekend. Saturday I was on YAHOO NEWS. There was a picture, a bold headline: SHOCKING SETBACK IN BIG OLYMPIC RACE and a subtitle which said Favorite in Men's 400 meter runs out before he crosses the finish line...and then....and THEN...it said "SPOILER ALERT" if you cared to click on the story.
Um. I think it was pretty spoiled at that point; as spoiled as that doggie bag you left in your hot car over the weekend.