Yep, Guiness. Cooked pretty simply, pour the beer into the slow cooker with the corned beef, along with the spice packet. I added potatoes, carrots, and onions partway through cooking. In a separate pan, heat bacon grease and olive oil. Add chopped kale, then cabbage. Ladle in the cooking broth from the slow cooker (and a slice of corned beef), simmer until done.