This is fairly simple, but you must be a pro at it to be successful. Find some people you know who have A LOT of coupons or go to the store and look for someone with A LOT of coupons. Simply wait until that friend of yours is sleeping or the person in the store is currently not by their shopping cart or paying attention and simply "accidentally" "borrow" all of their coupons. Now proceed to check-out with all your lovely coupons and buy everything you want even if you don't need it :)
(P.S. I can not be held responsible for the reactions or legal issues you might have to deal with after using this tip)
OH, and if they catch you, just say "Thank you for the coupons, I saved a lot of money!"