Here are some good ones, some shitty ones. But I like #4. Years ago I worked in an office where two guys named Chris had cubes next to each other. Their phones were connected to a central phone jack thing under the cubes. I simply swapped the jacks their cords went into. It caused endless confusion.., "hey Chris, it's bob. Where's that report?" It would take a couple of minutes to realize it was meant for the other Chris. Even longer for them to put it together.