The Rock Totally Surprised Zac Efron With A High School Musical Joke In Baywatch

But Efron played it cool

Only Dwayne "The Rock" Johnson can call Zac Efron "High School Musical" and get away with it.

In Baywatch, Mitch (Johnson) refuses to call new lifeguard Matt Brody (Efron) by his actual name. It's payback for Matt being such a dick, and it's one of the raunchy comedy's funnier recurring jokes. For example, he calls him "Baby Gap," "One Direction," "Bieber," and, costar Priyanka Chopra's personal favorite, "Malibu Ken." But the one that's sure to be a hit with audiences is "High School Musical."

According to Efron, the Disney Channel dig came as a total surprise on set. "It wasn't in the script," he told MTV News at the Miami press day for the film. "None of them were in the script."

But Efron took it like a champ. "He was so down with it, which made it work. I love that about Zac," Johnson said. "There's not a lot of movie stars, who are like, 'Yes! Make me the butt of every joke.' Plus, he's an easy target."

Watch Johnson, Efron, and director Seth Gordon break down the High School Musical joke in the video above. And check out Baywatch in theaters this Friday.