Make sure to go and like Old Navy on Facebook and there will be a little button that you can click to get the offer of $15 off $50. Once you click it, an email with the coupon will be sent to you. As far as I know, you can either print it out or have it on your smart phone, the cashier just has to be able to see what the code is to type it into the register. :)
Unfortunately, this offer cannot be combined with Super Cash, but you can do multiple transactions. Here are some other exclusions. Excludes GiftCards, Fruit of the Loom®, and charitable merchandise. Offer valid 10/26/2013-10/27/2013 only. One coupon per customer. Cannot be combined with other offers, including Old Navy Stuff & Save.