One-year-old Boo Boo the Chihuahua is Guinness Book of World Records' smallest living dog (in height). According to her owner in Raceland, KY, Boo Boo was fed with an eye dropper every two hours when she was a newborn one ounce pup. That's right—one ounce. I love her little expression which seems to say, "See the matchbox? I'm not much bigger. Love me, please."