My attempt at getting myself a free shirt:EDIT: Aw, just realized that National\'s not on fatwallet\'s list of CashBack merchants.Using coupon code NU2889JDP and rate code 5036929, it\'s possible to get a midsize as cheap as $1.50 for a whole weekend, including all taxes! Notes:rate code 5036929 is the code for american airlines; if you need to sign up, you can for free here.Coupon code requires you to use a visa card to purchase. Sometimes, National will request a copy of the coupon, so you can fi...