Shake Shack gets in on the Oktoberfest fun with their annual Shacktoberfest - back for the 9th year. The ShackBurger is great, but changing up your routine and going for a Brat Burger is better. Sometimes. Well, at this time of year anyway.

And so, from Oct. 5-12, celebrate the fall holiday with Shake Shack. Here's how:

Brat Burger: burger topped with a flat-top grilled bacon cheddar-stuffed bratwurst, crispy ShackMeister Ale-marinated shallots and curry ketchup. $7.50

Currywurst: Bavarian brat topped with crispy ShackMeister Ale-marinated shallots and curry ketchup. $4.95

Bavarian Brat: Griddled bratwurst topped with German-style slaw. $4.95

Bacon Cheddar Brat: Griddled bacon cheddar-stuffed bratwurst. $4.95

German Chocolate Walnut Concrete: Chocolate frozen custard blended with coconut-walnut caramel and chocolate truffle cookie dough. Single: $4.30; double: $5.75

Apfelstrudel Shake: Vanilla frozen custard hand-spun with apples, caramel and spices $5.75

You can also get a Shake Shack Bier Stein for $10, filled with beer. ($7 to refill.)

The brats are made by Schaller & Weber, the NYC-based butcher that's been making German sausages and meats since 1937. All special menu items will be available at all U.S. Shake Shack locations (excluding ballparks and airports.)