0shares Share Tweet Pin Expired Find current deals & events → A juicy burger and thick shake are always a sweet combo. Even sweeter, when you can get a deal. From Aug. 20 to Sept. 30, get a shake for just $2 at Smashburger, when you purchase a double burger at regular price. The offer is not valid on National Cheeseburger Day, Sept. 18, when the burger chain is expected to offer a special discount for the day. The offer is valid at participating locations and not valid with any other offer or discount. Plus, you cannot get the “shaky deal” on third-party delivery.