Zac Efron wore some of his skimpiest costumes to date and learned wrestling moves for his new movie Iron Claw. However, he handled both aspects of the project with grace.

On the other hand, the 36-year-old actor recently admitted that another element of the movie made him “very uncomfortable.”

What was worse than the costume? Here’s a hint: It involved his breakout movie High School Musical.

Read more about Zac Efron’s super uncomfortable Iron Claw moment…

During an interview with W Magazine, Zac revealed that his costar Harris Dickinson liked to sing High School Musical songs at him while they were filming.

“People like to do that to mess with me. It’s pretty funny,” he said.

However, “We had a scene where we show up to a party where Stanley [Simons], I think, is singing a song. He performed it live, and then they just continued to move on to another song, and it was something from High School Musical. I had to stay in character while that was going on, and everybody else was just losing it. The camera was on me, and I was just trying to stay in character. It put me in Kevin [Von Erich, the wrestler he played in the movie]‘s shoes a little bit. I felt very uncomfortable,” Zac admitted.

In the same interview, Zac did address the fact that he was nearly naked for the wrestling scenes. He also spilled on his first kiss.

If you missed it, another of Zac‘s Iron Claw costars made a shocking revelation about High School Musical.