I help setup computers for people who cannot afford to get shops to do so.
I setup 2 machines (desktop units, not mini towers) for a friend of my ex, and she took them home.
Later my ex calls me and asks me to talk to her. It seems that to her, the CD drive was installed upside down. The other computer was just fine. After a bit of quizzing, her USB connection was upside down as well. She finally got the point that the ENTIRE machine was upside down.
I have had people do strange things to their machines, but with 2 identical machines, turning one of them upside down and not realizing it is a new one for me!