Watch below: Holly Willoughby accidentally swears on This Morning
Leaving her co-host Phillip Schofield speechless and forced to apologise, Willoughby exclaimed "oh s***" after an on-air mistake.
The moment happened when Schofield and Willoughby — dressed for Halloween in Addams Family costumes — begun their latest Guess the Gadget segment.
As the challenge begun, they both attempted to guess objects and win points when Willoughby dropped one of the objects off the table.
She said "oh s***" before covering her mouth with her hand as Schofield pulled a face.
Willoughby then said: "Sorry. Sorry, sorry, I might have just... something might have slipped out, I'm so sorry."
Schofield added: "I'm so sorry. I think that Holly Willoughby might have sworn, and for that I can only apologise."
Willougby then joked that her Halloween costume had caused her bad language. "It wasn't Holly, it was Wednesday," she said before beginning a fit of giggles with Schofield.
For the Halloween edition of This Morning, all of the show's stars transformed into characters from The Addams Family.
Willoughby was dressed as Wednesday while Schofield dressed up as Uncle Fester. Alison Hammond also joined in on the fun as Morticia while Steve Wilson took on the role of Gomez.
Celebrity chef Phil Vickery, Gyles Brandreth and Gok Wan were also all dressed up as Addams Family characters.
The set of the show also received a makeover with spiders and cobwebs adorning the usually colourful studio.
This Morning's iconic titles and theme music were also given an Addams Family twist as the show got into a spooky spirit.
This Morning airs weekdays at 10am on ITV and ITV Hub.