The three-person relationship allegedly began soon after she met the famous musician at the Grand Havana Room in Beverly Hills in 2008 while he was dating Jennifer Aniston, according to Shay.
"I'm working this party, and I end up getting wasted with them," Shay claimed. "Every time they did a shot, they would get me a shot. I walked Jennifer to the bathroom at one point and then they invited me to go back to her place in the Palisades after for an after-party."
Shay said she skipped out on the invitation because she was too drunk to drive, but Mayer ended up coming back to the club weeks later after splitting with Aniston.
Soon she and her roommate at the time, Adams, started hanging out with Mayer, per Shay.
"This went on for about six months that we hung out," she said. "We would go to his house. It just became, you know, kind of the three of us. We had a little throuple going on. But then there was, like, me and another her. Everyone always had attention."
When asked by one of the podcast's host if Shay meant a "sexual throuple," she answered affirmatively.
"I definitely got a little jealous towards the end of it because I knew he liked her more," Shay said of Adams. "And I was like, 'Wait, I brought you into this, like and now you're getting more attention than I'm getting, like what's up with that?'"
"And then even after him and I stopped talking, they continued talking," she continued. "And there were like a lot of things -- like her and I had like a year of just awkward friendship falling out, but then came full circle a year later and -- have never been closer."
Shay then claimed she was fired from the club after another employee overheard her and Adams talking about Mayer, as it was against company policy to fraternize with club members and Mayer belonged to the New York branch.
And when the relationship between Shay and Mayer became public, she said she called him to tell him she did not leak the story.
"He was like 'No, it's cool, I don't think you would do that, like we've been hanging out for six months. Like, you probably would have done it by now.' And so I was like, 'You know I'm losing my job over this?' It was the week of my birthday. And I'm like, 'I don't think as a cocktail waitress we really get like a severance package.'"
Shay eventually landed her next job at Lisa Vanderpump's Villa Blanca, which led to her being cast on the Bravo reality show.
"So if it wasn’t for John Mayer, I wouldn't be on Vanderpump Rules," she quipped. "I never would have left that, that was one of the best jobs, still, that I've ever had at a restaurant."