HBO
You'd have to understand the show's Valyrian language to catch the joke.
In an interview with the show's linguist David Peterson - who helped create the series' multiple languages - admitted if you translate some of the show's dialogue, you'll be in for a treat.
One place you can spot a hidden reference is in a pivotal scene from this season's third episode, "Breaker of Chains."
In the scene, Daenerys Targaryen sends out her bodyguard Daario Naharis to take on a Meereenese man who proceeds to insult both Daenerys and Daario in the language of Low Valyrian.
Peterson revealed that the show's translation was not the same as what the man was saying. In fact, the actual translation gave a shout out to 1975's "Monty Python and the Holy Grail":
"One of the biggest is from Episode 3 this season. There's a scene where the Meereenese rider is challenging Daenerys' champion. He's shouting and Nathalie Emmanuel [Missandei] is translating - but she's not translating what he's saying. He's actually saying a Low Valyrian translation of the French guy's insults in 'Monty Python and the Holy Grail.' That was [series creator] Dan Weiss's idea and it was so hilarious that I had to do it."
In case you need to recall the classic scene from the film, check it out below:
Obviously, you'd have to understand the show's Valyrian language to get the joke, but Peterson went on to say that some fans did actually catch on pretty quickly.
"They know that something's going on," Peterson said. "Right after that episode aired, I was getting tweets like, "Is he saying a 'your momma' joke?" Close… But no, he's actually starting out with, "Your mother is a hamster."