Back in the early 2000s a family friend had come across this coupon that discounted $10 off any Duracell batteries that were over $10, so you would just have to pay the remainder. Well Home Depot, Target, Walmart etc...would sell this 2 pack of 9V Duracell batteries for around $10.13 after tax. Now once the coupon scanned the price would drop to 13 cents and you went on your way with the batteries.

The thing was that I printed out hundreds of these coupons with the expiration font so little that no cashier would be able to read it. Somehow, the register would scan the expired coupons even months after the expiration date.

So everyday I would make my rounds to all these stores just grabbing all the 9V Duracell batteries that I could find. Anytime I had around 10 of them I would simply return them without the receipt so they would just give me store credit. I simply turned $1.30 into $101.3 every return give or take. This was also the time where they wouldn't ID you if you returned too much product so I was raking in these store credits.

I also had some Doritos and Pepsi canned soda coupons that worked in a similar way. Lets just say I got a new TV, unlimited groceries from Walmart for 6 months and new tools from Home Depot all with those store credits.