The 'Snape Kills Dumbledore' meme stems from the massive cultural impact of the Harry Potter book and film series, specifically the release of 'The Half-Blood Prince.' Before the book's release, the phrase became one of the internet's earliest and most notorious spoilers, often shouted at people waiting in line or posted on forums to ruin the ending. Over time, it evolved from a genuine spoiler into a meta-joke representing the concept of 'spoiling' itself. Today, the meme template usually features the dramatic confrontation on the Astronomy Tower and is used to mock obvious conclusions or to ironically announce well-known facts as if they were shocking secrets.