Walking down the street last Saturday with my brother. We're carrying unopened copies of the seventh Harry Potter book.
Tom: You better finish the book over the weekend, or else Alipé will troll you on Monday.
Me: He does like to troll.
Tom: You'll walk into work, and he'll have been waiting for hours. He'll be shaking from waiting for so long.
Tom: You'll be ten pages from the end, and you'll sit down quickly to try to finish the book. Just as you get to the second-to-last page, Alipé will shout, "Harry dies!"
Me: Heh. [Note: That wasn't a spoiler; he just made it up.]
Tom: He won't just say it either. An IM will pop up on your monitor with it. It'll blare out from your speakers. He'll launch balloons that explode into confetti, and each piece of confetti will have a streamer that says, "Harry dies."
On Monday I told this to Alipé, who chuckled. "Tom has quite the active imagination!" he said.
He then told me that some people are so afraid of spoilers that they've written a Greasemonkey script, which scans each web page for names of major characters. If it finds "Harry", "Hermione", "Ron", it'll blot out the names with asterisks.
To combat this, some web pages are now authored to detect the greasemonkey script, and only show spoilers (worded in such a way to circumvent the script's rules) in the presence of the script.