When she was 12, Koko the gorilla -- who is able to use sign language -- wanted a pet. She got a stuffed animal. That wasn't satisfactory, so for her 13th birthday in 1984, she got a kitten, which she named All Ball. When the kitten died six months later, Koko expressed great sadness at her loss. She got two more kittens in 1985. Since the second one, Smoky, died in 2005, she's been getting cat visits from the Humane Society at her home at the Gorilla Foundation in Woodside, California.