I believe that cats do have a sence of humor, it is usually disclosed when they are playing. Their quick moves and alertness while playing with a favorite toy is proof enough for me. This probably accounts for kittens being so playful. Some cats do not "grow up", but remain kittens for at least 2 years of age. I have one cat who is continually playing with some toy and who is about 2 years of age (Chrissy). Chrissy is a traditional marble-swirl brown tabby with white underneath.