Kids are always gonna be like that, dumb and ignorant, everyone in the world has been there and done that.
Adults need to be calmer in those sorts of situations, but hey, we're only human, and can only take so much.
Anyone who might choose to use the phrase "Kids will be kids" in regards to this, IMHO, is using it as a cop out, since its a very cliche saying.
A kids lack of good manners and common sense will always fall back to parental responsibility.