The first ever acapella Number One on the Billboard chart was performed by Bobby McFerrin and featured in which film?
Simple Pleasures (Bobby McFerrin album):  It was his commercial breakthrough album, containing the hit single "Don't Worry, Be Happy," also featured in the film "Cocktail". Don't Worry, Be Happy:  Released in September 1988, it became the first "a cappella" song to reach number one on the "Billboard" Hot 100 chart, a position it held for two weeks.
Cocktail