Avril Lavigne will always have a happy memory of her time with ex-husband Chad Kroeger - every time she pees.

The two Canadian stars hooked up in 2012, when Lavigne's then-manager, Larry Rudolph, suggested she work with the Nickelback star on new music.

The odd couple fell in love in the studio and became engaged in a month.

They quickly wed and later separated, but Avril will always have the star constellation she impulsively had tattooed on her thigh to remember her ex by.

In a new Billboard interview, she admits she was drunk when she suggested that she and Chad should get matching tattoos and discovered the stars the following morning.

"I remember, like, peeing, and looking at it like, 'What the f**k did I do!? I love it'," she tells the publication.

Avril was criticised for romancing and then marrying the leader of one of rock's punchline bands, who most critics treat with disdain, but she still has his back, adding, "Chad’s band has sold, like, over 50 million albums! They’re selling out arenas worldwide!"

The couple split in 2015 but remain close - he produced her new single, Head Above Water, and several tracks on her new album, which marks her return to form after a lengthy battle with Lyme Disease.

She tells Billboard she was with her ex in his studio when she first started work on the new project, scared she'd no longer have the ability to hit the high notes: "But God was like, 'Nope, you're going to keep doing music'," she says, adding, "The silver lining of it is that I've really had the time to be able to just be present, instead of being, like, a machine: studio, tour, studio, tour. This is the first break I've ever taken since I was 15."