Sarah Jessica Parker found it "slightly peculiar" portraying Carrie Bradshaw again.
The 53-year-old actress teased the return of her iconic 'Sex and the City' character - who she last played in the second spin-off movie in 2010 - earlier this week and now her mystery project has been revealed as a Stella Artois commercial in aid of non-profit Water.org.
In the ad, which is set to the show's theme, the actress pays homage to the franchise's opening scene, donning a gold jacket and light blue tutu - a nod to the pink she wore in the 'SATC' opening - and gets splashed by a bus, which says "1 bottle = 1 month of clean water", rather than the "Carrie Bradshaw knows good sex" and her photo that is shown in the series, and she admitted it was "really fun" getting back into character.
She told HuffPost: "It's been a while. It was really fun. Slightly peculiar in the best possible way. It was especially meaningful because the purpose was to amplify this initiative."
Sarah agreed to get on board because of both the creativity of the advert and the cause itself.
She said: "I think just being right and clever about how they wanted to present Carrie for this particular idea -- I relied upon their good taste and the subversive nature of it.
"I think it's smart. ... In the past, you have a script and you have all the words you need to remind you if you've been away for a while. But this felt like an alternate universe. I was surrounded by smart and good people. It was really easy and really fun."
Meanwhile, Matt Damon - who founded Water.org in 2009 to help provide clean drinking water in developing countries - was delighted to get the 'Divorce' actress on board for Stella Artois' Pour It Forward initiative.
He said: ""It's going to have everyone's attention ... and that's a huge megaphone she's using to help this cause...
"As Carrie Bradshaw trades in her cosmo for a Stella, that's huge for us. And so it's all part of this same effort to really scale."
With every Stella Artois beverage purchased, a donation is given to Water.org.