To kick off their 10 Days of Deals promo, Redbox is offering a free DVD rental to all customers who check in on Foursquare at their local Walgreens. For an additional bargain – or for those who don’t have a smartphone –  text DEALS to 727272 and you’ll get a discount on a 1-night rental through Aug. 24. The discount amount may vary. The code for a free rental is only valid for a 1-night rental, and only valid today, at DVD kiosks at Walgreens stores.