Jim Carrey's co-star made grim admission about horror medical scare he had on Dumb and Dumber set

Jim Carrey has made a grim admission about what happened to him during filming 1994 comedy Dumb and Dumber.

It's nearly 30 years since the Jim Carrey and Jeff Daniels movie premiered in cinemas on 16 December, 1994 (the film's premiere took place 10 days earlier) and the flick has since been labelled a classic by fans.

The film tells the story of Lloyd Christmas (Carrey) and Harry Dunne (Daniels), two well meaning friends who set out on a cross country road-trip to return a briefcase - unaware that it was actually left as ransom money.

Jim Carrey and Jeff Daniels in Dumb and Dumber (New Line Cinema)

To celebrate the film's 30th birthday, actress Karen 'Duff' Duffy, who played the film's hitmen, shared a list of trivia about the film with PEOPLE - including a particularly grim medical scare which happened to Carrey while on set.

Turns out that Carrey had to take time off from filming after suffering a pretty grim gallbladder attack while on set.

"We were filming in the airport one day, and Jim doubled over and was rolling around," Duffy recalled.

Unfortunately for Carrey, it took crew a short while to take his pain seriously as several people thought he was just joking around.

Read more: Jim Carrey had to moon co-star on Dumb And Dumber set to help him get the right shot

"The reaction from pretty much everybody on set was, 'Oh, this is a prank. This is just Jim monkeying around'," the actress explained, before going on to reveal that an on-set medic finally realised he wasn't playing around.

This wasn't even the most bizarre part of the story either, as Duffy asked to actor if he'd give her his gallstones after they were removed in surgery - to which Carrey agreed.

However Duffy's plan to reuse the gallstones - which are hardened deposits of digestive fluid which form - as a gift for her co-star was never realised, as he gave them away before she could make it to the hospital.

Karen Duffy revealed the moment during an interview with PEOPLE (Santiago Felipe/WireImage)

"He said okay. I was going to make him a set of cufflinks with them. And then I went to visit him in the hospital, and he told me he'd given them to the girl he was seeing," she added.

Which is certainly an interesting gift to share with someone you're seeing, let's put it that way.

Duffy isn't the only Dumb and Dumber alum whose mentioned Carrey's gallbladder trouble over the years either, with writers Bobby and Peter Farrelly recalling the moment during promotion for 2014's sequel Dumb and Dumber To, revealing that the actor had to film a fight scene.

"The first day that he came back from the surgery, we had him do this fight scene with Jeff where they’re fighting over the briefcase and they’re rolling around," says Bobby explained to Hollywood Reporter at the time.

"It was the only night we could do it."