An American Werewolf In London

John Landis' horror movie from 1981 about two American tourists in London was one of the first in its genre with elaborate transformation scenes accompanied by an explicit soundtrack.

... We listen to a series of incredibly disgusting ‘snorks’ as the tiny mountains vanish up his nose. During a pause in HORACE’S computations, we hear the delightful sounds of HIS enthusiastic ‘CRYSTAL LUNCH CONSUMPTION’ over the intercom, followed by a series of EVEN MORE DISGUSTING sound effects (crunching bone matter and tearing human tissue, mingled with agonized groans vaguely reminiscent of the transformation sequences in “AMERICAN WEREWOLF IN LONDON”).

Them Or Us, page 145

... JIMMY snores and gags while the disgustingly realistic “AMERICAN’ WEREWOLF IN LONDON” sound effects are heard.

Them Or Us, page 161