The Jargon File (version 4.4.7, 29 Dec 2003):

gang bang
 n.

    The use of large numbers of loosely coupled programmers in an attempt to
    wedge a great many features into a product in a short time. Though there
    have been memorable gang bangs (e.g., that over-the-weekend assembler port
    mentioned in Steven Levy's Hackers), and large numbers of loosely-coupled
    programmers operating in bazaar mode can do very useful work when they're
    not on a deadline, most are perpetrated by large companies trying to meet
    unrealistic deadlines; the inevitable result is enormous buggy masses of
    code entirely lacking in orthogonality. When market-driven managers make
    a list of all the features the competition has and assign one programmer to
    implement each, the probability of maintaining a coherent (or even
    functional) design goes to epsilon. See also firefighting, Mongolian
    Hordes technique, Conway's Law.


The Free On-line Dictionary of Computing (30 December 2018):

gang bang

   The use of large numbers of loosely coupled programmers in an
   attempt to wedge a great many features into a product in a
   short time.  Though there have been memorable gang bangs
   (e.g. that over-the-weekend assembler port mentioned in
   Steven Levy's "Hackers"), most are perpetrated by large
   companies trying to meet deadlines; the inevitable result is
   enormous buggy masses of code entirely lacking in
   orthogonality.  When market-driven managers make a list of
   all the features the competition has and assign one programmer
   to implement each, the probability of maintaining a coherent
   (or even functional) design goes infinitesimal.  See also
   firefighting, Mongolian Hordes technique, Conway's Law.

   [Jargon File]