There are only so many situations in life when you hear the phrase “How ’bout a magic trick?” It’s pretty exciting when a magician says it, but not so much if it comes from some creepy guy on a park bench. But if that phrase is uttered by a homicidal maniac who happens to be one of the greatest villains of all time, it results in one one of the most memorable scenes from one of the greatest superhero movies ever. Now a decade after Heath Ledger‘s Oscar-winning performance in The Dark Knight, we finally have an answer as to how filmmakers made the Joker‘s iconic “disappearing pencil” trick a reality. No one lost an eye or a life during shooting, but it did cause some very real pain.

Today’s Nerdist News with Jessica Chobot looks at a new story in Vulture that gets down to the nitty gritty of the famous scene when the Joker stuck a pencil into a table before making it vanish via an eyeball. No, it wasn’t CGI, it was a practical effect that was a lot more dangerous than it sounds. But maybe not for the reason you think.

All these years we’ve been so focused on the pencil through the eyeball we never stopped to think about the head being slammed on the table. Somehow they came up with a (still far-too-risky) way to make sure the pencil was out of the way, but no one thought about how a human head repeatedly banging off a metal table might feel?

Magic tricks aren’t supposed to knock anyone out. Then again this was the Joker’s trick.

Are you surprised by how they filmed this scene? Does knowing how it was done change the way you think about it? Share your thoughts with us in the comments below.