Steve Martin, Tom Hanks and Martin Short have annual colonoscopy parties.

The three Hollywood stars are joined by a fourth friend once a year as the gather at the 'Planes, Trains and Automobiles' actor's home for an evening of poker and movies the night before they all go for the medical procedure, which sees a camera being passed into the bowel through the anus.

Opening up about their unusual gathering on 'Jimmy Kimmel Live', Steve explained: ''Yes, there's the Christmas party, then the colonoscopy party - that is true! We thought, everybody at our age... at a certain age, you won't to get a colonoscopy.

''It's after 50, right? We thought it would be easier, if it's all men and we celebrated... We play poker, we watch some funny movie, and you drink all the stuff.''

The four pals head to Steve's house each time, and Martin - who stars with his friend in new Netflix special 'An Evening You Will Forget for the Rest of Your Life' - joked they are turning it into a holiday of sorts.

He added: ''We're very excited, we go to Steve's house around 5pm the night before, we call it Colonoscopy Eve in Canada. And it's catered, there's jello.''

He even admitted they have a friendly competition each time, and make the card games more interesting by putting down a wager for the following day when they travel together to the doctors.

He explained: ''We actually play cards, and whoever loses goes last of the four.''