The slightly creepy reason Kate Winslet had to keep her socks on during her latest sex scene.

Kate Winslet is no stranger to a sex scene or two. With a number of accolades under her belt – and Titanic, you guys – she knows what she’s doing in front of the camera.

But while rubbing your naked bits against another person’s naked bits in front of a camera crew will probably never not be awkward for actors, that was the least of Idris Elba’s concerns while filming an intimate scene with his 42-year-old co-star in their upcoming film, The Mountain Between Us.

On tour promoting the film which sees Winslet’s and Elba’s characters stranded among some remote, snow-covered mountains after a tragic plane crash, the actors discussed the very unsexy mechanics behind making a sexy scene.

One of which, well, for Elba at least, included insisting Winslet keep her socks on during the deed.

“‘Keep your socks on’,” the actress told The Graham Norton Show, recalling the strange request her 45-year-old co-star made in regards to her clothes, or lack thereof.

“I’m like, keep my socks on? Everything else is off. What’s with the socks?” He was like, ‘I got a foot thing.’”

While Elba immediately admitted that, yes, he's got "a thing" about feet, it's probably not in the way you're thinking.

While most of us might associate a sock wearing demand with someone who hates feet, turns out it was more a preventative measure. For Winslet. Because the sight of her feet would've gotten Elba very, erm, excited.

"It’s the opposite, ladies and gentlemen," she said. "Idris loves feet." What Winslet is describing is more commonly known as a 'foot fetish', which involves a person becoming sexually aroused by the sight of a bare foot.

*shudders*

As the saying goes, each to their own, right? But we're really not sure we needed to know this about Idris Elba.

LISTEN: If you think a foot fetish is bad, wait 'til you hear porn star, Madison Missina explain what a 'crush fetish' is...