Just because someone is Chaotic, I don't think he doesn't have any moral codes. Perhaps he does have a moral code of his own, but he just doesn't care for the rules of the society, especially the ones that aren't inherently evil to break.

For instance, killing people is not something that can be measured on the "Lawful V.S. Chaotic" scale, it's something to be measured on the "Good V.S. Evil" scale.

Skipping school once in a while, doodling during tests, pulling off not-so-harmful pranks are probably points where "Lawful V.S. Chaotic" can be measured. They aren't necessarily evil actions, but you can tell they don't care for strict rules.