Stolen from another forum, I haven't verified it works because I don't have the mobile app:
"Save 20% off your hotel stay in Florida, Georgia, or the Carolinas by using the Expedia mobile app!
Coupon Code: MOBILEFL20
Offer: Receive an instant 20% mobile coupon discount off a hotel stay using the Expedia® hotels app on a smart phone or tablet. How to redeem: Access the mobile app on your smart phone or tablet and select a qualifying hotel stay for the following markets: Florida, Georgia, North Carolina, or South Carolina. On the hotel billing and delivery page you will see a drop-down feature that states "Enter a coupon or promotional code". Touch the drop-down feature and enter the code: MOBILEFL20. Instant coupons cannot be applied to guest registration bookings. If you do not have an Expedia.com user account, you must create one prior to making your qualifying hotel booking. Restrictions: Coupon must be redeemed on Expedia.com by 11:59 PM (Pacific Time) on June 17, 2013, for travel between June 11, 2013 – December 31, 2013. Limit one (1) coupon per user account and per qualifying hotel booking. This offer is from Expedia.com and is valid for Expedia.com U.S. customers only. Bookings are subject to availability at Expedia Rate hotels at the time of booking and all applicable terms and conditions. Coupon may not be used with other coupons, promotions or special offers. Coupon discount cannot be applied against taxes, supplier-charged fees, cancellation or change penalties, administrative fees or other miscellaneous charges, which are the sole responsibility of the customer. A coupon will be deemed fully used once a qualifying booking has been made and may not be reused. In the event that you change or cancel any part of your booking, the coupon will not apply to the changed travel schedule. Terms and conditions of this coupon are as written and cannot be changed by any representation of any unauthorized person, including employees of Expedia, Inc. Coupon is not transferable and is not redeemable for cash. Void where prohibited by law. Expedia, Inc. may revoke or change this offer at any time. "