Fill your grocery cart to the top with steaks and ice cream.
Tour the store casually for an hour.
Take your cart to check out and say you forgot your wallet. Opps. Sorry.
Shop with friends and family that do the same thing.
There are a million ways to jam up this fucked up system once you decide to stop being social and generally obedient. Things go south for retail very quickly.
Stop being good. You can effect their business legally and non violently.
Stop being a good citizen.