"It was fun," she said. "I mean I'm just trying not to laugh the whole time because he just makes me and everyone laugh so hard but - it was great, he's just so good. Watching him is a delight."
The film is about co-workers at a Chicago brewery who have feelings for each other. In addition to Wilde, the film features Jake Johnson, Anna Kendrick and Ron Livingston. Sudeikis' small role was a last-minute addition.
"We roped him in, he didn't know he was going to have to work," she said, adding that Sudeikis had come to visit her on the set before he went to shoot his own film, "We're the Millers."
"He came to lunch on set and I was like 'listen, we don't have anyone to play my boss. Will you just jump in and improvise with me for an hour?' He's like, 'yeah, great let's go,'" she added.
The actress - who is planning her wedding to Sudeikis - told Spencer that she's feeling good at this point in her life.
"I think the great thing about being a woman, turning 30, is that you understand that you're not living life for your parents or your peers. You're living life for yourself," she said.
She also talked about a recent article she wrote for Glamour magazine in which she talked about women turning 30. She encouraged women to travel, not be pressured to have kids and enjoy their sexual prime.
"I encouraged women to take advantage of it, to enjoy it to not be ashamed of it or stifle it. What I said in the article is that now we can act like an 18-year-old boy but just be better at everything," she said.
In the article, she also cautioned women against plastic surgery.
"There are too many young women who are cutting up their faces, and it makes me sad and they all look the same, and the article isn't meant to be preachy, it's as much advice to me as to everyone else, not saying I'm perfect," she said.