Missy Elliott Reveals What It Was Like to Watch Michelle Obama Rap 'Get Ur Freak On' for Carpool Karaoke

Michelle Obama’s Carpool Karaoke ride featured a very special surprise passenger – Missy Elliott!

The First Lady’s much anticipated appearance went public on Wednesday night’s episode of The Late Late Show with James Corden. The trailer promised some “Single Ladies” moves that would do Beyoncé proud, but fans were not expecting Mrs. Obama to show off her formidable flow by rapping “Get Ur Freak On” with the hip hop pioneer herself.

Elliott sat down exclusively with PEOPLE to reveal what it was like to rap and roll with the FLOTUS.

The pair first met back in March, when Elliott joined Obama for the keynote speech at South by Southwest in Austin, Texas. Though Elliott admits she was nervous, the First Lady’s warm welcome quickly put her at ease. “I remember her holding her arms out and coming towards me to hug me,” recalls Elliott, 45. “Everything ran through my mind like, ‘Wait ‘til my mama sees this! Wait 'til my cousins see this!’”

Things got even more presidential for Elliott in June when the Carpool Karaoke production took her all the way to 1600 Pennsylvania Ave.

“Just when you think you’ve reached the highest place, you find yourself pulling up to the White House and you’re walking inside a building that you’ve known about since you were a little, little kid,” she marvels. “They’re taking you around and showing you [things] – even down to the plates that each president might have eaten on. It’s like, 'Wow, can’t believe it.’”

It’s hard to imagine a more intimidating situation than rapping in a car with the First Lady while surrounded by a bunch of cameras, but Elliott took it all in stride. “I was probably more nervous about forgetting my words,” she admits. “[I was worried] I’d start mixing 'Work It’ with 'The Rain’ with 'Get Ur Freak On.’ But I wasn’t nervous about being in the car because they made me feel like they knew me.”

Turns out Mrs. Obama knows Missy Elliott – and her music – extremely well.

“When we got in the car and I saw her rapping 'Get Ur Freak On,’ it kind of bugged me out!” Elliott confirms that the FLOTUS indeed knew all the words. “I know for a fact that it was all over my face like, 'Wait, is she rapping this?’ But that goes to show you just how cool she is. People hold her in such a high regard – as you should – but she’s so down to Earth. I was just sitting in the back like, 'I gotta be dreaming. This ain’t even real. Is somebody going to wake me up and say, 'You overslept.’”

Safety concerns kept the car confined to the White House grounds, but that didn’t put a damper on the fast and loose mood.

“The way she is, you feel like you can just ride down the highway with the windows rolled down and be chilling with one of your friends,” Elliott tells PEOPLE. “But at the end of the day she is the First Lady so they probably thought it wasn’t a good idea to ride on the regular road.”

Famous for her elaborate music videos, Elliott says the taping was over in the blink of an eye. “It was cool because I didn’t know it was going to be one take. I’m thinking, 'We’re just rehearsing!’ And then they’re like, 'OK, we’re done!’ I was like, 'Whoa, wait a minute! That was the quickest I ever shot a video!”

The unforgettable TV moment was executive produced by AOL’s MAKERS.com, the same organization responsible for the First Lady’s girl power anthem “This Is For My Girls,” – inspired by the Let Girls Learn initiative and the 62 million girls around the world who do not have access to education. Mrs. Obama and Corden duetted on the song for Carpool Karaoke, but the recorded version features vocal appearances from some of the biggest names in the popular music, including Elliott herself.

“I wanted to be in support of Let Girls Learn so girls across the world could have education to become leaders and great mothers,” Elliott explains. “I don’t want my legacy to just be about music that I’ve done. I want it to be about great causes like this.”

In addition to aiding a worthy cause, Missy got the once-in-a-lifetime chance to get to know the First Lady on a personal level. “It’s one thing when you’re watching on TV but she’s so down to Earth. She’s like one of my aunts that would be at a cook-out. She’s so cool you almost forget! You almost gotta remind yourself, 'Hold up, this is the First Lady. You ain’t at the family reunion!’”