Pop star Halsey still can't believe she has become pals with good friend Katy Perry's ex John Mayer.

The odd couple met at a bar and hit it off, and now Halsey shares jokes with the Daughters singer online.

"We’re like platonic mates now," she tells Billboard. "If I think something is funny, I run it by him first, because he’s a comedic genius. He’ll tell me if it’s funny, but he’ll tell me if it’s not.

"I started answering people on Twitter by their first names. Someone will be like, 'Halsey f**king sucks', and I’ll be like, 'Stacy, wow, calm down'. He loved that."

And the young Canadian has also become friends with actor and rocker Jared Leto, insisting that's her "weirdest relationship".

"He’s stupidly smart," she says. "We met at Coachella. I direct my own videos, and I’ve learned so much from him about directing and acting."

She admits the Suicide Squad star helped her prepare for a top secret new movie role she has coming out next year (17).

"I can’t talk about it," she tells the outlet.