[ taken from the Jargon File ]

An important secondary meaning of {hack} is `a creative practical
joke'.  This kind of hack is easier to explain to non-hackers than the
programming kind.  Of course, some hacks have both natures; see the
lexicon entries for {pseudo} and {kgbvax}.  But here are some examples
of pure practical jokes that illustrate the hacking spirit:

     In 1961, students from Caltech (California Institute of
     Technology, in Pasadena) hacked the Rose Bowl football game.  One
     student posed as a reporter and `interviewed' the director of the
     University of Washington card stunts (such stunts involve people
     in the stands who hold up colored cards to make pictures).  The
     reporter learned exactly how the stunts were operated, and also
     that the director would be out to dinner later.

     While the director was eating, the students (who called
     themselves the `Fiendish Fourteen') picked a lock and stole a
     blank direction sheet for the card stunts.  They then had a
     printer run off 2300 copies of the blank.  The next day they
     picked the lock again and stole the master plans for the stunts
     -- large sheets of graph paper colored in with the stunt
     pictures.  Using these as a guide, they made new instructions for
     three of the stunts on the duplicated blanks.  Finally, they
     broke in once more, replacing the stolen master plans and
     substituting the stack of diddled instruction sheets for the
     original set.

     The result was that three of the pictures were totally different.
     Instead of `WASHINGTON', the word ``CALTECH' was flashed.  Another
     stunt showed the word `HUSKIES', the Washington nickname, but
     spelled it backwards.  And what was supposed to have been a picture
     of a husky instead showed a beaver.  (Both Caltech and MIT use the 
     beaver --- nature's engineer -- as a mascot.)

     After the game, the Washington faculty athletic representative
     said: "Some thought it ingenious; others were indignant."  The
     Washington student body president remarked: "No hard feelings,
     but at the time it was unbelievable.  We were amazed."

This is now considered a classic hack, particularly because revising
the direction sheets constituted a form of programming.

Here is another classic hack:


     On November 20, 1982, MIT hacked the Harvard-Yale football game.
     Just after Harvard's second touchdown against Yale, in the first
     quarter, a small black ball popped up out of the ground at the
     40-yard line, and grew bigger, and bigger, and bigger.  The
     letters `MIT' appeared all over the ball.  As the players and
     officials stood around gawking, the ball grew to six feet in
     diameter and then burst with a bang and a cloud of white smoke.

     The "Boston Globe" later reported: "If you want to know the
     truth, MIT won The Game."

     The prank had taken weeks of careful planning by members of MIT's
     Delta Kappa Epsilon fraternity.  The device consisted of a
     weather balloon, a hydraulic ram powered by Freon gas to lift it
     out of the ground, and a vacuum-cleaner motor to inflate it.
     They made eight separate expeditions to Harvard Stadium between 1
     and 5 A.M., locating an unused 110-volt circuit in the stadium
     and running buried wires from the stadium circuit to the 40-yard
     line, where they buried the balloon device.  When the time came
     to activate the device, two fraternity members had merely to flip
     a circuit breaker and push a plug into an outlet.

     This stunt had all the earmarks of a perfect hack: surprise,
     publicity, the ingenious use of technology, safety, and
     harmlessness.  The use of manual control allowed the prank to be
     timed so as not to disrupt the game (it was set off between
     plays, so the outcome of the game would not be unduly affected).
     The perpetrators had even thoughtfully attached a note to the
     balloon explaining that the device was not dangerous and
     contained no explosives.

     Harvard president Derek Bok commented: "They have an awful lot of
     clever people down there at MIT, and they did it again."
     President Paul E. Gray of MIT said: "There is absolutely no truth
     to the rumor that I had anything to do with it, but I wish there
     were."

The hacks above are verifiable history; they can be proved to have
happened.  Many other classic-hack stories from MIT and elsewhere,
though retold as history, have the characteristics of what Jan
Brunvand has called `urban folklore' (see {FOAF}).  Perhaps the best
known of these is the legend of the infamous trolley-car hack, an
alleged incident in which engineering students are said to have welded
a trolley car to its tracks with thermite.  Numerous versions of this
have been recorded from the 1940s to the present, most set at MIT but
at least one very detailed version set at CMU.