What is the meaning of Crackerjack?

Exceptionally fine or excellent; top-notch; high quality.

Expert, top-rated or high-performing.

An exceptionally fine or excellent thing or person.

An expert or top-rated individual (e.g., a marksman).

Referring to clothing items (pants, jersey, collar) that constitute the traditional blue uniform of the enlisted men of the US Navy.

The traditional blue uniforms of the enlisted men of the US Navy.

A U.S. Navy sailor.

Popcorn candied in molasses-flavored caramel and peanuts.

Source: wiktionary.org