Ever wondered what it’s like when a celebrity films a category for Jeopardy!? These segments usually tie into the star’s upcoming project, and they read the clues off for the contestants in a similar category.

How to Train Your Dragon stars Gerard Butler, Nico Parker, and Mason Thames filmed a category for the game show. and told CinemaBlend that it wasn’t as easy as it looked.

Parker shared that the nature of the questions and the teleprompter made the job a bit challenging, but her costar also didn’t make it easy. Thames “threw stuff” at Parker to get her to mess up. He also pranked her during her two questions and said that it worked.

“We did when we had some content days in LA, and one of the things that we did was Jeopardy!. But it was actually really difficult because half of the words are really small and quite difficult, and I remember we were reading off a teleprompter and I’m like, ‘I have no idea what I’m saying,’” Parker revealed.

“It was [also] very stressful. Mason was off camera, staring at me while I did it, so I kept messing it up. It was so embarrassing.”

Thames only read one question, while Parker and Butler read two. See the clues above in “Viking Lore.” Host Ken Jennings joked that he couldn’t compete with Butler’s accent after he gave the introduction.

The actors told the outlet they filmed the clues during a regular press day. The category aired on the June 16 game featuring Kate Kornacki, Sarah Cox, and Tom Thriveni, just days after the live-action remake of the 2010 animated film hit theaters on June 13.

Jeopardy!, Season 42, September 8, check local listings