Grease star John Travolta shocked fans by strolling out dressed as Danny Zuko at a sing-a-long event for the hit 1978 film in Los Angeles. The 71-year-old actor starred as the charismatic T-Bird opposite Olivia Newton-John as angelic Sandy Olson in the hit musical.

"Grease," based on the hit 1972 Broadway musical of the same name, follows Danny, a local bad boy, and Sandy (Olivia Newton-John), a wholesome high school transfer student from Australia, as they reunite at Rydell High School after meeting at the beach over the summer.

Fans at the 'Grease' Sing-A-Long screening at the Hollywood Bowl last night got a surprise when the original Danny Zuko strutted out onstage.