Jennifer Lawrence admits to almost killing someone while messing around on set.

There is a time and place for everything.

And when you’re filming on the side of a mountain and there are people below you, it is NOT the time to use a rock to scratch your butt.

Jennifer Lawrence experienced a close call when she chose this inopportune time to scratch an itch on the set of one of the Hunger Games films and almost killed a sound guy.

“We were filming in Hawaii, and there were sacred rocks,” the actress told host Graham Norton while appearing on his show.

“You’re not supposed to sit on them.”

But of course, the 26-year-old did, and took it a little bit further, dislodging one of the rocks in the process.

"I however, was in a wetsuit... Oh, my god they were so good for butt itching," Lawrence said.

"One rock ... ended up coming loose.

"It was a giant boulder, it rolled down this mountain, and almost killed our sound guy."

Luckily, he was out of the way before the boulder landed and survived to become part of a talk-show anecdote.

The Oscar-winner was on The Graham Norton Show to promote her new film Passengers, a sci-fi flick about two travellers in suspended animation who wake up 90 years before they are supposed to.

While promoting the film, her co-star Chris Pratt has been making fun of Lawrence's lack of social media use - posting selfies with the leading lady cropped out.

Finally got that selfie with Jen y'all wanted. #passengersmovie

A photo posted by chris pratt (@prattprattpratt) on Nov 29, 2016 at 7:06am PST

My publicist Allison just took this hilarious candid photo. Totally startled me and #JenniferLawrence. It's little moments like this I'm so glad to be able to share with our fans as we promote #passengersmovie

A photo posted by chris pratt (@prattprattpratt) on Dec 2, 2016 at 8:41am PST