Margot Robbie has lifted the lid, or rather unscrewed the ointment cap, on her bizarre beauty obsession.
The Wolf of Wall Street actress is a fan of regularly using an $8 nipple cream loved by new mums the world over.
But she doesn't rub it where you would expect. The homegrown Hollywood 'it' girl dabs the product on her lips.
"My lip balm, I use Bepanthen, which is actually a nipple cream for breastfeeding mothers or diaper rash cream for babies," Robbie, who found fame in the soap Neighbours, told Elle magazine.
"I have a conspiracy theory that lip balms actually have additives in them to dry your lips out so you keep buying them. But because Bepanthen is just a cream for dry skin, it works."
It certainly looks like it does work - Robbie's pucker is pretty and picture perfect.
The ointment is sold primarily as a treatment for nappy rash in babies, but its creator Bayer also promotes it as soothing relief for mothers with cracked, dry nipples from breastfeeding.
Robbie's use of the unconventional lip treatment isn't a recent routine - the Gold Coast native said she has used it "my whole life".
Bepanthen sells for about $8 at chemists and is found in nappy bags across the world.