Heigh Ho is the name of the song from Snow White And The Seven Dwarfs (1937).
In the movie, Gremlins (1984), at the Kingston Falls Movie Theatre, the gremlins watching "Snow White". and the seven dwarfs sing "Heigh Ho". This then lead the gremlins singing the song too. At the snack stand, Gizmo (with Billy and Kate) hears and sings the song as well. At the end of the movie, "Gremlins", as Mr. Wing takes Gizmo back home, he (inside of the ancient box) sings the same song from "Snow White".