The Free On-line Dictionary of Computing (19 January 2023):

Hacking X for Y

   [ITS] Ritual phrasing of part of the information which ITS
   made publicly available about each user.  This information
   (the INQUIR record) was a sort of form in which the user could
   fill out various fields.  On display, two of these fields were
   always combined into a project description of the form
   "Hacking X for Y" (e.g. ""Hacking perceptrons for Minsky"").
   This form of description became traditional and has since been
   carried over to other systems with more general facilities for
   self-advertisement (such as Unix plan files).

   [Jargon File]


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

Hacking X for Y
 n.

    [ITS] Ritual phrasing of part of the information which ITS made publicly
    available about each user. This information (the INQUIR record) was a sort
    of form in which the user could fill out various fields. On display, two of
    these fields were always combined into a project description of the form “
    Hacking X for Y” (e.g., “Hacking perceptrons for Minsky”). This form of
    description became traditional and has since been carried over to other
    systems with more general facilities for self-advertisement (such as Unix 
    plan files).