Name that theme song: Dunnn-dun. Dunnn-dun.

Dun-dun dun-dun dun-dun dun-dun.

Who are we kidding? That terrifying two-note John Williams creation of course conjures the opening shark strike in “Jaws,” which turns 50 on June 20.

That’s a half-century of scaring the bejesus out of generations of movie- and beachgoers. Five decades of us all scanning the horizon for fins while Hollywood thrashes about trying to replicate Steven Spielberg’s blockbuster, from “Shark Week” to “The Meg.”

Full confession: Seeing “Jaws” kept me not only out of the ocean for years but also out of a pool. I’ve even heard of people who were scared to get into a bathtub.