Dunder Mifflin employees get in the spirit of Halloween. (Bottom, from left) Erin, Angela, Kevin, Kelly and Oscar.

Through six seasons of “The Office,” we’ve been introduced to the dark side of the Dunder Mifflin staff.

Kevin is a degenerate gambler.

Meredith has sex with terrorists.

Andy has anger control issues.

Ryan had a drug habit.

Phyllis likes to get busy in public places.

Michael dates much, much older women.

Oscar has been known to skip work when (gasp!) he’s not actually sick!

Kelly has been known to lie, and cry, to get her way.

Pam longed for Jim while engaged to Roy.

Angela “dated” Dwight while engaged to Andy.

Creed … Well, this blog is only 500 words, so we’ll have to move along …

Stanley cheats on his wife.

Dwight is completely devoid of morals. And he owns a beet farm.

And then there was Jim, who seemed to be the exception to the rule. Good, ol’ smirking Jim Halpert. Mr. Dependable. Mr. Honest.

Then came the Koi Pond Incident, and we learned that, when a friend is in need, he leans. He leans far, far away.

“Koi Pond” opens with Dunder Mifflin hosting a haunted house in the warehouse. Darryl – aka “Gangsta Pumpkin” – leads the children of the Scranton Industrial Park community through a tour that includes a frightening group of characters, including Dwight as a clown and Jim as “Bookface.”

Michael ends the tour with an important message regarding suicide, which is something that should stick with the youngster for years to come, no matter how many hours of therapy they undergo.

A client asks for Michael to visit their business, not realizing that Jim is co-manager. The client insists that Michael come along on the sales call as well, which annoys Jim.

Andy and Pam also go on a sales call, where each of their potential clients mistake them for a couple. After Pam’s initial reaction of humor mixed with revulsion, Andy gets back at her by saying that his girlfriend – who is “a 9 on the scale from 1 to Gisele” – hired Pam to be their surrogate.

“My girlfriend needed to keep her figure for fashon week, so we put our baby in Pam,” Andy tells a client. “It doesn’t matter what she looks like.”

Surprisingly, they don’t land the client.

Finally, the “couple” decides to play along, which goes horribly awry when Andy gets far too up-close-and-personal with Pam’s baby, and, by extension, Pam.

Michael and Jim return to Dunder Mifflin and the staff notices that Michael is soaked and Jim is not. Michael admits that he fell into a koi pond in the lobby where they made their sales call. The staff, of course, can’t resist making flounder and carp jokes at Michael’s expense.

Michael – who is used to being the face, not butt of jokes – calls a sensitivity training meeting where staff list what they are most ashamed of about themselves, including Dwight’s tiny nose, Kevin’s huge gut, Angela’s squirrel-like eating habits and Meredith’s habit of bedding terrorists.

Jim convinces Michael to joke around with staff about his inadequacies, but that makes it even worse as Michael relives the four times he was tossed into the frozen lake by his high school’s girls volleyball team and the fact that he couldn’t come up with five friends for his cellphone plan.

Meredith secures a copy of the security tape that has Michael taking a dip. While the staff is anxious to watch it, Jim tries to talk them out of it. But even Michael is OK with it.

And the tape reveals … Jim is a leaner! With his friend staggering, Jim didn’t reach out to help. He just let him make a big splash!

With Jim revealed to be a modern-day Judas, there is only one Dunder Mifflin employee who seemingly is sweet, honest and pure as the driven snow.

The problems with Erin is that her dedication to Michael is kinda creepy, her affection for Andy is inexplicable and she is far more familiar with the cinematic work of Marlon Wayans than of Marlon Brando’s.

So what did you think of the episode? Are you surprised by Jim’s selfishness? Do you hope Andy and Erin hook up? Whenever you see Dwight, are you going to think, “Man, he really does have a little nose!”