http://www.cnn.com/2005/LAW/08/03/girl.charged.ap/index.html
Boy throws water ballon at girl. Girl throws 2 pound rock at boy hitting him in the head, and he had to have stitches to close the wound.
She is charged with assault with deadly weapon, which some feel is inapropriate.
Seems to me the choice of escalating the event from water ballons to rocks was inappropriate.
But maybe she thought there was bad stuff in the water balloons.