Early 20th century term meaning "Excellent", used for a caramel coated popcorn-peanut treat

Cracker Jack or crackerjack

Explanation:

Crackerjack is the slang term that means something is excellent and admirable, being it a person or a thing. For example: "He is really crackerjack in his field of expertise."

It is the term also taken for the branding of certain caramelized popcorn. Cracker Jack is an American brand of junk-food, one of the first that ever existed, for pop-corn and peanuts coated with caramel dressing, also made famous for a treat inside the package.