My first cat when I was little said "Mom". He got it off of me. I swear, true.
People used to call on the phone or come over and ask did we have a baby in the house. "Why? Do you hear someone calling Mom?" They nodded. "It's our cat." They would then give us that "what's the number to the local nuthouse" look, and we'd bring the cat in and eventually he would do it, and they'd nearly fall off their chairs.