One time I was fixing my father in laws PC and came accross a folder, in which I had to peek. It was rammed full of porn, all nicely categorised into sub folders too. Considering the amount of calls I've had from him along the lines of, "I saved a word document and now I can't find it", I was amazed at how organised all this was. Then the penny dropped. There never were any, "word documents".
It also reminds me of a story I read on a forum once about the young lad who's parents were away on holiday. He had a few mates round to watch a porno on his dads new plasma. After they left he went to bed. The next morning he woke up to find that he hadn't turned the DVD and TV off. When he did he was greeted by some lovely screen burn of the films naughty menu screen.
It's probably an urban legend, but it always makes me laugh.