My cat is crazy.
Let me explain the reason for his mental retardation: Back when he was a kitten (about 12 weeks old), he was outside with his mom and brother. Something spooked him and so came running along the deck and turned to run into the house and, of course, bounced off the glass sliding door. He looked at the door like it was some magical force-field. He then ran to the back of the deck, turned around and booked it toward the door, probably thinking in his little kitty mind that if he just ran FASTER he could make it through the clear force-field. Obviously he ran head first into the door. Since then, the cat will scratch glass panes. It's probably started as him pawing at the doors and windows to see if there was something there and of course, since we would open whatever he was pawing at, he learned that if he wanted to go out, he needed to scratch the door.
Now, if it stopped at this point, it would make some sense. But it doesn't. He has since decided that any sort of glass or reflective surface is fair game. So he scratches the dishwasher door if we're ignoring him, he scratches the marble tiles in the bathroom if he's stuck in the bathroom, he scratches the mirror if he sees it. He also will scratch at the glass shower wall. From the inside. And we don't put him in there. Nor do we block his way out.
Now, I just need to figure out how to get him to do it on command so I can film it and post it here. Then I need to figure out how to put little scrubbies on his paws. Then we could tour the nation and he could clean peoples' showers. He'd totally be famous. Like the cat in the Staples "Copy Cat" commercial.