The Grease star plays a politician's wife who snorts lines of cocaine in this week's comedy, which stars Xavier Samuel, Kris Marshall and Kevin Bishop.
Newton-John said that director Stephen Elliott (Priscilla, Queen of the Desert) was the main reason why she wanted to appear in the movie.
"It is fun to do something unexpected - it is acting after all!" Newton-John said of her drug-fuelled comedy scenes in the film.
On modern-day movie comedies she enjoys, the actress and singer said: "My husband and I loved The Hangover, and I love romantic comedies and will watch anything with Woody Allen or Diane Keaton, and lately Meryl Streep."
A Few Best Men opens in UK cinemas today (August 31).
Watch the film's trailer below: