A really mean trick was pulled on me one day. I had been working on an orbit propagation program for an IBM 360, and had this huge card deck stack. I had been debuging it for days, and late one night someone popped in and substituted it with a bunch of random discarded cards and then the next morning "accidentally" knocked the box off my desk scattering these cards all over my office! LOL! After about an hour they fessed up and gave me my program still intact. :-)
He he he.
We had engineering work that was run at Stanford during the night and this "happened" all the time.