John Travolta made a surprise appearance at Friday night's "Grease" sing-a-long at the Hollywood Bowl dressed as his iconic drag racing, hip swinging 1950s bad boy Danny Zuko. "Tonight at the Hollywood Bowl, for the first time I surprised everyone at the 'GREASE' Sing-A-Long and dressed up as Danny Zuko," Travolta wrote in anInstagrampost Saturday, sharing a video of his appearance. "No one knew. Not even the cast. Thank you for a great evening." More from Variety Hugh Jackman Recalls Bombing Audition Singing 'Stars' From 'Les Misérables' 30 Years Ago: 'I Cracked on the Final Note So Spectacularly' Cynthia Erivo Laughs Off Conservative Backlash to Her Playing Jesus on Stage: 'Why Not?... It's a Musical, the Gayest Place on Earth' Adam Lambert to Play Judas in Hollywood Bowl Production of 'Jesus Christ Superstar' View this post on Instagram A post shared by John Travolta (@johntravolta) In the video, Travolta swaggered on stage as the leather-clad greaser, as the packed Hollywood Bowl erupted in cheers. Travolta then greeted the other original cast members on stage, who were stunned themselves to see him, before addressing the crowd. "L.A! I thought you were going back to Australia?" Travolta joked, referencing the iconic line from the classic movie musical. "That's cool, that's cool, baby. You know, rocking and rolling and whatnot." After a three-count, Travolta and the rest of his former castmates then sang in unison with the crowd, "a-womp-bop-a-looma a-womp-bam-boom." The "Grease" star then said to the audience, "Enjoy the show. We love you!" Joining Travolta on stage were director Randal Kleiser, Barry Pearl, Didi Conn, Barry Pearl, Kelly Ward and Michael Tucci. Released in 1978, Travolta starred in "Grease" alongside Olivia Newton-John, who died in 2022. Other cast members include Stockard Channing, Jeff Conaway, Jamie Donnelly, Dinah Manoff and Eve Arden. Made for only $6 million, the film became Paramount's highest earner by the end of its run, with a gross of more than $130 million. Best of Variety New Movies Out Now in Theaters: What to See This Week 'Harry Potter' TV Show Cast Guide: Who's Who in Hogwarts? 25 Hollywood Legends Who Deserve an Honorary Oscar Sign up forVariety's Newsletter. For the latest news, follow us onFacebook,Twitter, andInstagram.