Jack Black is looking back on his experience on the set of School of Rock.

The 54-year-old actor starred in the 2003 hit with a much younger cast. In it, he plays a substitute teacher who introduces music to the classroom.

In a 20-year retrospective, Jack explained why he was nervous about filming the project. One of his castmates also recalled a time that he apologized to all of the parents and their children on set.

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“In retrospect, it seems ridiculous, because I’m such an immature idiot that it was a perfect match to be with a bunch of kids,” Jack told Rolling Stone. “We had a blast — horsing around and making jokes and making fart noises in between takes.”

Co-star Jordan-Claire Green chimed in to recall an experience with Jack.

“The only time I ever saw him get nervous was one night we were on set, and he said a cuss word,” she shared. “I think it was ‘s-it.’ He apologized to our parents. My mom was like, ‘You don’t think she’s ever heard me say ‘s-it’?’”

Rivkah Reyes chimed in with more memories of Jack. “He was just very, very fun. And really, he does have a young spirit. He was a big kid, but not in a man-child way, more just a kindred energy,” she said. “And he did a really good job of balancing professionalism and personality — not being the diva star lead, first on the call sheet, show up and do the shots and then leave. He was there with us between takes.”

Did you know that Jack is eligible for an Oscar for a song he contributed to another musical movie?