Or if you have cats that need to rub themselves against anything. It's especially confusing at night, when you can't even see it happen because one of your cats is black.

Fortunately my cat usually avoids my desk (I move him off it if he decides to walk/lay on it, and he seems to have learnt not to - he now curls up on my bed (just behind my desk) instead). He did trigger the 360 drive button a few times when he first moved in* though, so I can imagine the annoyance.

* Long story, but he originally belonged to a neighbouring house a few streets away. We fed him _once_ (didn't recognise where it was from, and it looked as though he had been trapped somewhere for a while - he was covered in cuts and was filthy, as if he had be struggling to get out of somewhere), and after that we couldn't get rid of him. He kept appearing (usually multiple times a day) for three months or so, even though we wouldn't feed him, let him in the house, or pet him (as we knew he had an owner at that point). Even after his owner moved and took him with her (about three miles away), he kept finding his way back, so eventually his owner suggested that we take him in.