Maybe it's the aspect of "getting away with something?"
Antisocial people have difficulty distinguishing between morality and arbitrary rules. If you ask normal kids if, say, the teacher announces that class rules have changed, and you're now allowed to talk during class, they will agree that it would therefore be acceptable to do so, and the psychopaths would agree. However, if the teacher announced that the class rules against cutting classmates with scissors were canceled, only the little Digibros and Diddler Daxes would think that really made it OK to do.