I don't know who taught Katie to say it, but she keeps going around saying, "bad baby" in a stern tone of voice. Not to anyone in particular, just sort of chanting it. Brianna used to say it to her and we'd get onto her about it constantly, but I haven't noticed her doing that in some time.
Granted, Katie is rather destructive and randomly violent like most 1 year olds, but at least she's usually cute about it. At any given moment you can find her taking down one of her big brothers with a flying body tackle or giving a karate chop to her sisters. She likes watching "Xena: Warrior Princess" late at night with me and gets excited when Xena takes out the bad guys. If you say, "hi-YA" and make a chopping motion on her she'll pretend to flop over with her tongue out making a dying sound. Then she'll want you to do it, too.