Today only, McDonald's is giving away 200 FREE Limited Edition Bottles of Big Mac Special Sauce on the McDonald's on facebook at 2pm ET (1pm CT, 12pm MT, 11am PT). They are also giving away free bottles at select participating restaurants in the United States. Click here to view the list of participating locations. When in the restaurant, customers must give a code — “There’s a Big Mac for that” — to employees to for their chance to take home a bottle of the sauce. If you have an iOS device, you can download the new Big Mac Special Sauce Finder iMessage app to find participating locations.