I was working at a Community College, back in the 70's, running programs thru punch cards on a shared mainframe (which serviced all the colleges in the state), and developing some Fortran software for an automatic-random-question-test system for a professor. Anyways, I wasn't sure how a certain loop would output, so I needed to run through about 1000 simulations. Well, being a dummy, I made each loop to be a separate process, instead of all under one process and I overloaded the process_queue on the mainframe, and shut the whole works down. The professor and sys-admin were quite annoyed because they were blamed. :-)

What did I learn? I learned..."don't do that again" :-)