SPOILER ALERT: Do not read if you have not yet watched the second episode of “Westworld” Season 2.

Yes, that really did happen.

On Sunday night’s episode of “Westworld,” Bernard (Jeffrey Wright) and Stubbs (Luke Hemsworth) sneak back into the park’s tech corridors to investigate why Maeve (Thandie Newton) has gone missing. Instead, they discover that none other than Drogon, the fire-breathing star of HBO’s recently concluded juggernaut “Game of Thrones,” is apparently a robotic attraction the park’s Medieval World. Not only that, but “Game of Thrones” executive producers David Benioff and D.B. Weiss are working as technicians in the park, trying to figure out how they can abscond with Drogon to Costa Rica.

What? And how? And what?!

As “Westworld” showrunners Lisa Joy and Jonathan Nolan explained to Variety in an interview in their Los Angeles offices on Feb. 27, the married couple have been friends with Benioff and Weiss ever since they first met as “Westworld” was shooting its first season. And it turns out “Game of Thrones” author and mastermind George R.R. Martin was also involved.

So how did you get David Benioff and Dan Weiss to do this?

Jonathan Nolan: Those guys are the f—ing nicest guys in the world. Usually when you come into a network where there’s a big dog show — and we’ve been in that position before — without naming names, there’s been [a vibe of], “We’re not inclined to be friendly to you if you’re the new kid on the block.” We came to HBO with a big ambitious show at a point in which their show was and is the biggest f—ing thing that’s ever been on TV. And they were so welcoming and so kind to us at a moment in which we were struggling through a first season and trying to figure out how it will work. We’ve remained friends.

Lisa Joy: And then we repaid them by making fun of them! [Laughs]

Nolan: We’re also friendly with George R.R. Martin, and George had consistently since the first season said, “We’ve got to do a tie-in with ‘Game of Thrones.'” People forget that George was originally a TV writer and he came up in the TV world in which you’d occasionally have these crossover shows, which the fans would f—ing freak out over. So George had always been pitching the crossover show.

Wait, George had pitched the idea of a “Game of Thrones”-“Westworld” crossover?

Nolan: Oh yeah!

Joy: But like a full situation. “Game of Thrones” world, or something!

Nolan: And if he lived in Los Angeles, we would surely have insisted that he come and hang out on our set as well. But the crossover with the existing Medieval World in the original [“Westworld”] movie [released in 1973] was just irresistible. And the amount of people, starting with George, who over the years had pitched some version of a crossover. We just — we couldn’t resist. And [David and Dan] were incredibly good sports about coming down.

Joy: I had to see them in those tech suits, too.

Nolan: Yeah, exactly. They were fully up for it, and we had a really fun evening having them down and on our set.

Joy: The funniest reaction was Dave’s wife, Amanda Peet. So lovely and talented and brilliant. And she writes to me and she’s like, [Nolan starts laughing] “You needed an actor. And the person you called was my husband, the worst actor of all time?!”

Nolan: I think he’s terrific!

Joy: Yeah, they’re good.

Who came up with the idea that they’re trying to steal Drogon and take him to Costa Rica?

Joy: [Looks at Nolan] I think that was you. That’s the kind of weird s— that gets you going.

Nolan: I pitched it to them, as sort of, “How would you guys feel about this?” And they thought it was great fun.

Getting Drogon in there — I’m not quite sure if this is how CGI works, but could you just copy and paste their dragon into your show?

Nolan: Very kindly, we were working with their vendor, Pixomondo, who built the dragons for them. So it’s the real dragon.

Joy: We had to choose. I remember there was a whole big debate about which season dragon for its size because the dragon grew.

Nolan: There was some back and forth about whether Season 4 or Season 5 Drogon, and some debate about how big the room was and what position the dragon could be in. But yeah, it’s just irresistible.

And just to be clear, because I think there’ll be a lot of speculation about this on the internet, you guys aren’t creating the “Game of Thrones” world in the show?

Nolan: [Laughs] I guess that’s definitely open to speculation. [Smiles] No, we couldn’t.