John Travolta celebrates 40th anniversary of ‘Grease’ at Cannes

After unveiling his new film “Gotti” at a black-tie Cannes Film Festival premiere on Tuesday, John Travolta wore a jean jacket and black T-shirt to a beach screening of his 1978 classic “Grease” the next night for fans.

Travolta — a big Hollywood presence at Cannes this year — introduced the movie with festival head Thierry Frémaux and “Grease” director Randal Kleiser to mark its 40th anniversary.

“There were 1,000 people singing every line with Travolta as they watched on the beach. It was like karaoke,” said a guest. “People were wrapped in blankets. Travolta was having the best time.”

We hear the star flew his own plane into town after vacationing in Ireland with his family, including wife Kelly Preston, kids Ella Bleu and Ben, and sister Ellen Travolta.

After the festival, he’ll start shooting a new film, “The Poison Rose,” next week with Ella Bleu, as well as Morgan Freeman, Forest Whitaker and Famke Janssen.

With all the attention surrounding Travolta when he hit the red carpet for “Gotti” — he was also on the carpet for “Solo: A Star Wars Story” on the same night — a pal told us the star’s young son, Ben, 7, “had a bit of a freakout” with all the hubbub. “But seeing his father up on-screen stabilized him.”

At a festival master class, Travolta recalled of his 1994 Cannes-winning film “Pulp Fiction”: “Quentin [Tarantino] always saw me as an unpredictable actor.

He said, ‘If I wanted predictability, I would have chosen someone different.’ ”