1 1/2 oz of Bacardi 151 rum (or overproof rum)
8 oz of can mug root beer (or dark beer)
1/2 oz of aftershock hot & cool cinnamon schnapps (or cinnamon schnapps)
Fill an iced beer mug halfway with ice cubes. Add Bacardi 151, then Aftershock, followed by an entire can of Mug root beer (or until mug is full). Stir briskly with a spoon and serve.