Meghan Trainor is one in-demand artist at the moment, which isn't surprising since her hit "All About That Bass" is sitting pretty at #1 on top of the Billboard Hot 100 charts.

The Nantucket native has burst onto the scene with her body-empowering anthem that has swept the nation with its positive message. Now, we all want to know what's next.

The singer is readying her next single, "Title," an upbeat throwback track that shows off Meghan's rapping skills and gives another powerful message: If you want to get with her, then you better give her that GF title.

But, in between gearing up for her second single, traveling the country and covering Taylor Swift's "Shake It Off," the 20-year-old is working hard on her debut album, which already features a pretty big name collaboration.

"Here it is, John Legend," she told us at the iHeart Radio Music Festival. "I'm freaking out."

While Meghan didn't tell us what the song title was, she did reveal that the track was actually something that she'd written a few years back and had no intention of putting it on her album.

"I wrote the song like years ago and it wasn't going to make my album but my Uncle Burton Toney, the man, my Trinidadian uncle [he is married to Meghan's aunt] he met my managers and forced them to listen," she said. "He said you need to hear this song, she didn't show you this song, you need to hear it. And I thought because it wasn't shoo-wop vibey I blanked out, and the girl, my manager, listened to it and started crying and she's like 'You know you've got to cut this, right?'"

She continued, "So then I cut it, I produced a version with my friend and they sent it to John because he's on my management company and he's like 'I love this I want to be a part of it'...It's gonna be cool."