As Game of Thrones begins its eighth and final season, a HBO web-series reveals an anecdote involving co-creator David Benioff and star Jason Momoa.

The latest episode of HBO Backstories, an animated web-series detailing behind-the-scenes tales from the network's popular series, has Benioff and co-creator Dan Weiss recall an encounter with Momoa during production of Season 2 in Belfast. After filming a cameo for Momoa appearing from beyond the grave as Khal Drogo in a dream sequence, the creators, Momoa, Emilia Clarke and Alfie Allen celebrated the shoot with beers at a local pub where Momoa spoke about beating a friend in a slap game that had the two target each others hands. Spurred by liquid courage, Benioff decided to challenge Momoa to the game.

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"I'm looking at Momoa and Momoa's talking about beating someone at the slap game," recounted Benioff. "I was like, 'I'll take you at the slap game.' I was like, 'I'm going to challenge the Khal, because if I beat the Khal, I am the Khal.'"

The good-natured competition began with the two taking turns slapping each others' hands until one missed. Despite Momoa's noted strength, Benioff endured for caught some time until his hands were bright red. The following morning, the co-creator's hands had swollen to double their normal size, prompting him to visit to go to the hospital upon his return to Los Angeles to ensure nothing was broken in his failed bid to usurp the Khal.

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Airing Sundays at 9 p.m. ET on HBO, Game of Thrones stars Peter Dinklage as Tyrion Lannister, Nikolaj Coster-Waldau as Jaime Lannister, Lena Headey as Cersei Lannister, Emilia Clarke as Daenerys Targaryen, Sophie Turner as Sansa Stark, Maisie Williams as Arya Stark and Kit Harington as Jon Snow.

(via Entertainment Tonight)