Warning: This post contains spoilers for Episode 14 of theOffice Ladiespodcast.

Over the course of The dit nhau 18 tuoiOffice’s nine seasons, the show gave us some of the greatest cold opens in television history.

The NBC comedy became known for mastering cold opens — those short beginning sequences that precede the theme song and opening credits — but it turns out the hilarious moments weren't always scripted.

On the latest episode of the Office Ladies podcast, former co-stars Jenna Fischer and Angela Kinsey talked about how the cold open in "Performance Review" featured an iconic Jim Halpert moment that wasn't written orimprovised, it was completely accidental.

In case you need a refresher, "Performance Review" kicks off with a shot of Jim and Dwight at their desks. Dwight is distracting Jim by bouncing up and down on his new "fitness orb," which he claims has "completely" changed his life and revolutionized his ab workouts.

As Dwight goes on about core strength and the benefits of using an exercise ball, which include "more enjoyable sex," Jim grows increasingly annoyed, and after learning the orb only costs $25 he decides to stab it with a pair of scissors.

In the brilliantly executed scene, Jim quickly pops the ball and Dwight goes crashing to the ground, but that wasn't the way things were supposed to play out.

"Ladies and gentleman, it was not meant to pop," Fischer said when discussing the exercise ball. "I traded messages with Phil Shea, props master, and he told me all about the fitness orbs."

"First of all, he bought 17 [orbs] and he practiced with John using three of them. The idea was that John would stick the scissors into the fitness orb, it would deflate very slowly, and the camera would be in front of Dwight’s desk and you would see him just very slowly sort of melt to the floor as Jim very smugly [looks on]. That was what was in the script,” she said.

"So they practiced three times, it worked perfectly. And they had 14 [orbs] left for the scene, and Phil said to John, 'as long as you don’t hit the seam of the ball with the scissors — which would be like a one in a million chance that you could do it — the ball will slowly deflate, and it will work as planned.'"

"They did 13 takes and it worked just right and everyone was ready to move on," Fischer said, but Shea decided to remind everyone he still had one more ball left. Director Paul Feig replied, "Oh what the heck, let’s just do one more," and that's when the magic happened.

"In all the 13 takes, Rainn slowly sunk to the ground," Kinsey said, but on the last take, John accidentally hit the seam of the ball with the scissors and the entire thing popped.

"You can see the shock on Rainn's face, and he fell to the floor," Fischer said. "We were all completely shocked, like, 'oh my god.' And you can totally see John break — his shoulders — and very quickly, [because] he’s such a pro, he turns his back and just like leaves."

If you rewatch the scene above you can actually see Krasinski gasp, put his hand over his mouth, and jump out of frame. It's an absolutely beautiful sight, and in a 2007 interview with Esquire,Krasinski even said it was one of his favorite pranks in the show.

"He fell down and hit his head. If you watch the episode again, I literally lunge out of the frame because I'm laughing so hard," Krasinski told the publication.

According to Fischer, the episode wasn't going to feature the accidental ball-popping shot, but when they went to edit the footage and put in the slow, scripted deflate, Larry Wilmore, who wrote the episode, fought to use the blooper. "That is an example of a perfect cold open," Fischer said.

Wilmore — who, in addition to being a writer, is also a comedian, producer, and actor best known for creating The Bernie Mac Showand his work as a correspondent on The Daily Show. He called into the podcast to talk with Fischer and Kinsey about the memorable cold open, The Officewriter's room, and what it was like playing Mr. Brown in Season 1’s "Diversity Day" episode.

You can stream episodes of The Officeon Netflixand follow along with the podcast every week on Earwolf, Apple Podcasts, or Stitcher.