Game of Thrones isn’t usually in the habit of high-profile cameos. Sure, over the past few seasons we’ve seen pale, bearded members of Coldplay, Snow Patrol, Sigur Ros, and Mastodon crop up in the background, but to this point no strikingly familiar faces have shown up buried under a layer of Westerosi dirt. But all that might change this year. Friends of the show Charlie Day and Rob McElhenney (a.k.a. two of the stars of the FX comedy It’s Always Sunny in Philadelphia) have been spotted near the Game of Thrones set this week, and we have reason to believe this could be more than just a friendly visit.

In an interview earlier this year, co-creator David Benioff revealed which of their many celebrity fans they would invite to have a cameo on the show. Benioff said, “We’re trying to figure out a way to get some of our ultimate-fighter friends on the show. We think that would be fun . . . and of course Rob McElhenney and Charlie Day from Always Sunny . . . they want to.“ His partner D.B. Weiss broke in, ”We want to make it happen.” Benioff replied, “We’re trying to figure it out.” For those who don’t know, Weiss and Benioff actually wrote an episode of It’s Always Sunny in Philadelphia back in 2013.

At the time, the Sunny cast members told The Hollywood Reporter that they’d have to return the favor with McElhenney joking, “It turns out it’s not that hard to do our show,” and Day responding, “I guess we’ll have to do a Game of Thrones, we’ll see.”

Weiss and Benioff have kept in touch with McElhenney, who showed off his fan cred by hosting a Game of Thrones panel back in 2013. And you can see them seated together with McElhenney’s wife and Sunny co-star Kaitlin Olson behind Arnold Schwarzenegger here at a U.F.C. match this past May. So when Day and McElhenney showed up in Belfast last week, it seemed like something more than a friendly visit could be in the cards. You can see a photo of Day with some Irish fans below, and one of both McElhenney and Day here.

The only wrench in this otherwise splendid theory is that McElhenney is looking a little too clean-shaven for my liking. If he really were in Belfast in order to film a quick cameo, wouldn’t some Westerosi scruff be in order? (And we know McElhenney can rock the scruff.) So maybe they’re just hanging around the set for fun. (Seems to be a popular activity these days.) Or maybe it’s time to add Day and McElhenney’s beards to the #KitHaringtonHairWatch2015