It takes its name from a repeated line in the film referring first to Jack Sparrow ("He's a pirate!", exclaimed by Weatherby Swann, to which William Turner replies with "And a good man!") and later to William Turner as Elizabeth Swann's final line in the film.
The cue also appears on Epics: The History of the World According To Hollywood as "Pirates of the Caribbean". A series of remixes were released on a CD entitled "Pirates Remixed". A thirty second excerpt from Drop Zone, called "Too Many Notes-Not Enough Rest" (also composed by Hans Zimmer), had been frequently used in movie trailers (most notably The Mask of Zorro and Pirates of the Caribbean: The Curse of the Black Pearl), and He's a Pirate bears a strong resemblance with this particular cue.
Kingdom Hearts II Version
He's a Pirate
This track is also called "Drink Up Me Hearties" on the film's complete soundtrack.