The two used to star alongside each other in 'That 70s Show', and are once again sharing the limelight as Mila makes a guest appearance on Ashton's show, playing a character named Vivian.
During their scene, the pair make light of their real life relationship, with Mila joking that Ashton's character must "only date actresses", to which he replies: "No... they're all crazy".
They continue to make light of the furore that constantly surrounds their relationship, and the speculation from earlier this year about whether they were engaged, as Mila asks: "Who cares who's dating who, or who's engaged to who?"
Things then quickly heat up as she adds: “...Or who has a sex tape that no one will ever, ever see?”
Now you’re just teasing us, Mila.
This isn't the first time a joke about Ashton's real life relationship has made it into the show, as his character has previously claimed he likes Angelina Jolie better than Mila.
Ashton joined the sitcom in 2011, after actor Charlie Sheen was fired for his inappropriate off-screen antics.
There’s now speculation that he and Mila might be expecting their first child together, although it’s yet to be officially confirmed.