Everyone knows that The Office had a phenomenal main cast, but never forget that the series featured a number of truly impressive guest stars as well.

One of those guest stars was Rich Sommer, who played Pam's art school friend, Alex, in two Season 5 episodes of the show. You may know Sommer as Harry Crane on Mad Men, too. And he's also the latest guest on the Office Ladiespodcast.

Sommer spoke with Office Ladies co-hosts Jenna Fischer and Angela Kinsey about Mad Men, the "Business Trip" episode of The Office, how he got hired on the workplace comedy, and more.

How Rich got into art school on The Office

Fischer and Kinsey love asking podcast guests how they first started working on the show, and Sommer had a particularly interesting casting story. He got the part of Alex thanks to writer and actor Mindy Kaling.

"To my recollection Mindy and I met at the SAG Awards when you guys and the Mad Men cast were nominated," Sommer explained. "Mindy was a fan of Mad Men and came up to me, and I was so excited to meet her... but she came up to me and said, 'Hey I'm writing a part with you in mind on the show. Would that be OK?' And I was like, 'Yes!' because, you know, like everyone else, The Officewas one of my favorite shows on TV..."

Sommer explained that someone fromThe Officereached out and offered him the role of Alex after they'd written the part, and he accepted immediately. He also revealed that he'd auditioned for the show once or twice before, but didn't get those roles. Thankfully, it all worked out in the end.

Strictly friends or something more?

In their quest to determine whether or not Alex was meant to be a full-on love interest for Pam or really just a friendfrom art school, the co-hosts asked Sommer how the role was pitched to him.

"Well, this is the meaty part of the conversation I suppose," he said. "The way it was pitched to me was... 'We think this is a character who's going to be [here] throughout this season. We think it's a character that's gonna be kind of like Rashida's character, where it might be another road bump for Jim and Pam.'"

Aha! Jim knew it.

"So when it started that was definitely what was in my mind. But we filmed scenes that didn't make it into the show, and I started to kind of put it together that the response from the audience," Sommer continued. "They were not pleased. And who could blame them after what they'd been through for four seasons?"

Several riskier Pam and Alex storylines wound up getting cut from final edits but live on today in deleted scenes reels. Ultimately, Sommer feels Alex's storyline was "aborted," but he totally gets why and agreed that him coming between Jim and Pam would have been "too much."

"I remain delighted that I had the parts that I had," Sommer reflected. "How I feel about it is that it's a very funny interesting way to have been part of The Office legacy."

Filming wasn't all laughs

Though The Office is a delightful comedy, it turns out filming wasn't all laughs for Sommer.

One of the episodes that Alex was in, "Customer Survey," was directed by Stephen Merchant, the genius who co-created the original British version of The Officewith Ricky Gervais. Needless to say, there was some added pressure on set.

"Did you crap your pants when you found out Stephen Merchant was directing?" Fischer asked.

"Yes. It was upsetting," Sommer laughed.

Sommer then revealed that he had "a mole" on the set of The Office who sent him an original version of the "Customer Survey" script, in which his character Alex professed his love to Pam.

The lines were obviously changed later on, but Sommer wasn't able to shake the original Alex vibe, and it ended up messing with his head during shooting.

"I couldn't get it out of my head because everything we'd been playing is that Alex had crush on Pam," Sommer said. "…In the moment I couldn't find the right level of demonstrative that Stephen wanted. And the level that Stephen wanted was zero, and the level that I was continually pumping out was more in the neighborhood of like 75 percent demonstrative."

"I couldn't reel it in, and in fact, Jenna, to your question of pooping my pants when I found out it was Stephen Merchant, that was just a little jitter compared to how I felt when Stephen came up to me after a take and said these words, the words that have haunted me as an actor forever," he continued.

"[Merchant] came up to me and said: 'I don't know why you're not getting this," Sommer explained. "It was awful. He was, by the way, 100 percent right. I just couldn't do it. So looking at Jenna Fischer standing across from me, John Krasinski is crumpled up into a ball under a table in that room reading his lines for the Bluetooth...and I'm just like mortified. Like, 'This is it! I'm never acting again, obviously!'"

Though Sommer may have had a stressful day on set, Fischer and Kinsey stressed how much the cast loved him and his performance. And he lived to act again, and again, and again. A happy ending!

Be sure to listen to the full podcast episode for more behind-the-scenes stories about Rich Sommer, the friendships between The Officeand Mad Mencasts, and the "Business Trip" episode.

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