Next time, ask them the questions I always ask badgefags:

"Hey, how do you know which laws don't apply to you when you wear the costumes? Like, it's totally illegal to possess heroin, but when you put the costume on, you can possess heroin if you steal it from a regular person at gun point and also kidnap them and lock them in a cage. Is it like that with every law? How do you know? Does the costume come with some sort of user manual that tells you which laws don't apply anymore when you wear it? I'm confused, can you explain how that works for me."