The nerds of The Big Bang Theory love sci-fi and fantasy. Game of Thrones is the biggest fantasy TV series of all time, so naturally they're into it. They talk about it all the time, as you can see in the video above.
In fact, there was a whole Season 9 episode, "The Viewing Party Combustion," based around the gang watching an episode of the HBO show. Stuart (Kevin Sussman) even showed up in a Jon Snow costume, which set up Raj (Kunal Nayyar) to make the show's best-ever Game of Thrones joke when comparing their night to the show: "Stuart's dressed like a member of the Night's Watch, and they don't have sex."
And who could forget Leonard (Johnny Galecki) and Sheldon's (Jim Parsons) Game of Thrones sword, which they bought in Season 5's "The Russian Rocket Reaction" and has hung on the wall of their apartment ever since. The presence of Jon Snow's sword Longclaw in the background means there's kind of a Game of Thrones reference in every episode. All men must die, bazinga.
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