A lot of the animals at pet stores are from puppy or kitty mills. I prefer to adopt from a shelter an animal that would otherwise not have a home. My puppy, for example, would probably have died run over by a car, or starving if we had not taken him.
Yes, I have heard of animals doing odd things like that. My cat loves to go in bags. A coworker told me that once, one of her cats got into the trash bag, her husband closed it, and was ready to take it outside, when she noticed that one of the cats was missing. They heard the trash meowing, and there was the cat. If she hadn't noticed before, he would have ended up in the dumpster by mistake.
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"Of all God's creatures, there is only one that cannot be made slave of the leash. That one is the cat. If man could be crossed with the cat it would improve the man, but it would deteriorate the cat." - Mark Twain