Today everybody has a network connection in the office. And the majority of people are quite heavily dependent on their connections during the day. In other words if their connection is down they get quite frustrated quite fast.
My colleague was one of these people and he got very upset very fast. I always dreamt of situation were my network connection was working and his was not. So… One day when he had already left the office I took the cable from his docking station and gently cut the cable vertically with a razor and chopped the green wire. Be sure to cut the cable from a spot that is under the table or otherwise out of sight. Then I put just two drops of instant clue to the inside of the covering and gently closed the covering.
The next day he spent half a day cursing his connection and calling to the help-desk. One might automatically thought that the rational thing is to check the cable, but who would assume that the cable just breaks down by itself one day… Well I had quite an amusing morning listening his cursing and swearing the it-department… After a couple hours he finally checked the cable in enough detail to discover the cut =)