When software, movies, music, etc. is acquired through piracy.
Captain Jack refers to Captain Jack Sparrow of the "Pirates of the Caribbean" films.
The "Jack" part of the name is also a play on the word "jack" or "to steal".
"Not with my Captain Jack discount!"
"There's thousands of songs on your iPhone! You must have financed Steve Job's funeral yourself by buying these on iTunes!"
"iTunes? HELL no! I got these off the internet with my Captain Jack discount."