Before the turn of the century, I had a short IT support gig at an university. After getting one classroom rewired, the uni network staff noted that both the panel-to-switch and socket-to-computer Ethernet cables were of the crossover type, and wanted to fix that, by swapping both to straight/normal ones. It was fine otherwise, except that the panel-to-socket connections were mislabeled, and I ended up breaking three or four Ethernet cards on PowerMac 7200's. It is a triple WTF: first, the mislabeling from panel-to-wall socket cabling; that was just pure evil. Second, that using a crossover cable instead of a straight one, or vice versa, could break the network card on PowerMacs 7200s. Third, I didn't realize what was happening until I broke the third one (or might even have been the fourth).