From what I've seen, those "Extreme Couponing" shows and what not rely on flaws in the wording on the coupons. Most of the time people take advantage of it so they can get tons of gallons of mouthwash, or something mundane like that. Well the other day, Best Buy had such a flaw in the wording of one of their deals, and ended up giving away thousands of dollars worth of merchandise. Check out the link here for more info: http://www.businessinsider.com/best-buy-coupon-fail-2013-1
Needless to say, someone got fired over this one.