The other day I caught Josie really giving it to Bart. Well, when I say "giving it to him" - I mean she was slapping at him around with the force of a small winged bird. And she was smiling. Not intimidating in the least.
She also talked to him the whole time and helped him up (without adding the extra "ha! take that!" that's he's used to).
The gentle push over was also very brutal. I think it's safe to say Josie isn't cut out for hand-to-hand combat - which is actually a good thing.