Juicy J Gave Katy Perry a Verse... And 'Some Grillz'?

Perry's sole Prism collaborator tells MTV News the story behind 'Dark Horse.'

Katy Perry may have been letting the light in on her just-released Prism, but that doesn't mean she couldn't bring out her dark side as well.

"Dark Horse," inspired by the 1996 film "The Craft," is a menacing dance track on which Perry plays seductress and puts a potential lover under her spell.

But she's not going at this track alone: Perry enlisted Juicy J, the lone feature on the album, to lay down a verse. And when MTV News recently caught up with Juicy he gave us the full story behind the collaboration.

"Dr. Luke gave me a call and was like, 'Hey man, Katy Perry wants you to feature on one of her songs for her album' and I was like, 'Wow.' I couldn't believe," Juicy J said before admitting that Perry is a big fan of his Stay Trippy track "Scholarship." "He sent me the track over, I did the verse and like a week later he called me again and he was like, 'She wants to meet you she wants you to come to the studio.' "

Juicy J and Perry met up in the studio where she was "very professional," but the recording process was something new for the rapper.

"It was a little different. I did a lot of different versions to it. I recorded almost three verses because I wanted to make sure everything fit with the song and that she was satisfied," Juicy J said. "So it was a little challenging to make, but I've been doing this for a long time and I had fun doing it so it wasn't a problem."

Yet, it seems that Perry, who has described the track as "witchy, spell-y kind of black magic-y idea," was more than thrilled with the end result, even having an impromptu sing-a-long with her collaborator.

"When we finished the whole song we kept listening to it listening to it over and over again," Juicy J said. "And she was singing all the lyrics to my flow to my verse on the song and I was like, 'Wow.' Just to be there with Katy Perry a huge artist like that it's great."

And it seems like the studio session went so well that Perry walked away with a lot more than just a verse.

"It was great. She liked my chain and I hooked her up with my jeweler. She wanted to get some grillz, so I gave her the contact to my jeweler," Juicy said. "But it was cool."