By Kathleen Perricone

Sir Mix-A-Lot made headlines this week for his song “Baby Got Back,” more than 20 years after it was first a major hit, when he performed the classic backed by the Seattle Symphony.

And the rapper called in to On Air with Ryan Seacrest on Thursday morning to tell us how the viral moment went down.

“It was kind of weird,” he explained. “Gabriel, who composed everything, I met with him two years ago and he’s like, ‘I want you to do this thing live with an orchestra.’ And of course I started shaking, but I thought I have two years, this guy is probably a flake. It will never happen … and it happened.”

And although he’s performed the 1992 classic a billion times, Mix was very nervous about this one.

“To be honest with you, and nobody believes this, when I went down there to rehearse, I was very nervous I wouldn’t be able to pull it off. Let’s face it, you’re talking about fans of orchestral stuff mixed with my fans. I was hoping it’d be more of my fans, but it ended up being a 50-50 mix.”

As for the his backup dancers, who really added to the performance, Mix says that was all impromptu. “I asked the maestro prior to going on … I said, ‘Do you mind if I bring some people onstage?’ and he said, ‘No problem.’ I don’t think he expected 40 women, so it was all organic. It was nothing planned.”

So what kind of reaction did Sir Mix-A-Lot get from the orchestra, who normally play a very different kind of music?

“When we did our first rehearsal, they were very stoic. By that night, I gave them big props from the stage, they were going nuts. Now they’re rock stars.”

And if you were wondering if Mix still has a thing for big backsides, he tells us, “As I got older, my standards have lowered for obvious reasons.”