I'm sure many of you have seen the infamous Etherkiller on the web, as it was passed around eons ago. I still am amused by people hooking live 110 Volt AC up to data circuits, as long as it isn't my equipment.
A quote from the site:
"It all started one day with this guy, the origional Etherkiller, developed with a few misc parts to warn new users that the IT department is not to be messed with. You too can make one at home, connect the transmit pins of the RJ-45 to HOT on 110VAC and the recieve pins to Common. Modify to suit case by varying pinout."
W00T! For the young ones, you might want to reference The Bastard Operator From Hell, to find out why some maladjusted lads enter the IT workforce in the first place.