The bombshell was dropped on Tuesday's episode of "Watch What Happens Live with Andy Cohen," after a caller asked Rinna if she had been approached to join the bougie and entertaining ensemble prior to her start date in 2014.
"Would you like to tell the story, Andy?" the former soap star asked her boss. "Let's tell the story."
Visibly uncomfortable, Andy began, "We did talk to Lisa at the beginning -- Season 1 -- and put her on tape. I felt very strongly, for better or worse, that... I felt like it was... I didn't get it."
Poor Andy did not expect to be put in the hot seat.
"I felt like it should be all unknown people, even though Kim and Kyle [Richards] had acted years before or whatever," he continued. "I felt like Lisa Rinna was too much of a personality and name. And then, by the way, I will say, when you did join, I was the biggest [supporter]. I was like, 'It is time for Lisa Rinna to join.' You had been on ['WWHL'], I knew that you knew the women, you had a long history. I just felt that the show needed to establish itself on its own before, in my mind, I could ever picture it."
Rinna reassured her stuttering boss that she "totally" agreed with his decision, adding, "Everything happens for a reason. Always."
"When we were looking at casting for Season 1 of New York Housewives, Bethenny [Frankel] was on the casting, and I was like, 'She was just on 'The Apprentice: Martha Stewart,' and I thought, 'I don't get it. She just was on a reality show. People are gonna think she's just going from reality show to reality show. I don't get this.' I was not in favor of Bethenny coming on, so I've made some mistakes in my life."
At least you can admit them, Andy!
The late-night host then switched gears to focus on his iconic, Housewife-studded baby shower that took place last month in Los Angeles. He asked Rinna if she had planned on taking over the mic and ordering everyone to dance on tables. She did not, but she was mighty proud.
"That happened so accidentally!" she said. "At the very end, they said, 'You guys have to leave.' So I said, 'One more dance, please! One more dance.' And that's when I got on the mic, and I started screaming at everyone so that we could celebrate you!"
"I got 50 Housewives on a table. How about that? 50! I got everybody," she added. "I would've never guessed that in a million years."
Check out more fun facts about Rinna's experience at Andy's baby shower in the Q&A below.
On a scale from 1 to 10, how drunk were you at the shower?
"I was highly buzzed."
What did Harry and your kids think of your dancing?
"You know, they see me do that anyway. They all think I'm crazy anyway. Nobody had any reaction to it. None! Zero."
Were any Housewives throwing shade behind the scenes?
When John Mayer showed up, which Housewives were the most into getting over to talk to him?
"It was all the OGs. All the OGs were around him."
Any Housewife that you thought you wouldn't get along with but you wound up really enjoying their company?
"I liked all of them. NeNe and I -- love NeNe. I loved Ramona! Ramona I love!"
Which Housewife killed it fashion wise?
"Oh, gosh, I don't know. All of them! Kyle. Kyle, but her suit was ruined. That poor suit!"