British actor Tamer Hassan struggled to learn lines in a fictional language for his upcoming role in Game of Thrones.
The Layer Cake star plays a Dothraki warrior in the sixth season of the popular fantasy TV show, and he had to perfect the tribe's dialect instead of saying his lines in English.
Hassan admits he was daunted by the task of getting to grips with Dothraki, which was created by Game of Thrones writer DB Weiss and linguistics expert David J Peterson.
"When you join the cast, you get a page and learning the Dothraki was so difficult," he told British newspaper the Daily Mirror.
"It's the most challenging thing I've had to do. It's a whole new level of learning - like going back to school... It's basically like French, Spanish and Arabic with a mad accent all rolled into one."
The actor revealed he was terrified about making a mistake because fans of the show would pick up a language blunder.
"There's no way you can wing it because all the die-hard fans will be after you," he added.
Peterson previously said he and Weiss lightened the mood onset by translating gags by comedy troupe Monty Python into one of the fictional languages featured in the show, and inserting them into the script.
"There's a scene (in season four) where the Meereenese rider is challenging Daenerys' champion," Peterson revealed.
"He's shouting and Nathalie Emmanuel (her character 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 Dan Weiss' idea and it was so hilarious that I had to do it."
The Monty Python insults featured in Game of Thrones are said to include phrases such as "Your mother was a hamster and your father smelt of elderberries", "Go boil your bottoms, son of a silly person!", and "I fart in your general direction!"