During her Wednesday appearance on Conan, Turner revealed that she and Williams, who played Sansa and Arya Stark, respectively, would troll the show's cast and crew by trying to kiss each other on set.
"We fully knew [that people thought we were together]. We played into it. We did," Turner explained to host Conan O'Brien of her close relationship with Williams. "So on the set, we would kind of do the scene then try and kiss each other in the middle of the scene and see if anyone would react."
"It's Game of Thrones, so incest is so normal that they were like, 'All right, that's fine,'" she continued. "It was probably the most tame thing that happened on the show, actually."
O'Brien followed up, asking if Turner and Williams were just trying to make people think they were dating each other as a joke. "Yeah, you know, sometimes you just wanna make out with your best friend," Turner teased.
The co-stars quickly became best friends after being cast as sisters on the HBO drama as children. In fact, Williams will be a maid of honor at Turner's upcoming second wedding to Joe Jonas. Turner shared the news with ET at Game of Thrones' season eight premiere in April.
"I don't know why she's thinking about [what she's wearing to my wedding]. I'm giving her the bridesmaid dress!" she said with a laugh. "She's my maid of honor! One of two."