Place the ham in the basin of a slow cooker.
In a small saucepan, combine 1/4 cup of the brown sugar, cola, and mustard over high heat.
Bring to a boil and make sure the sugar has dissolved.
Pour the mixture over the ham. If your ham is pre-sliced make sure some of the glaze goes in between the slices.
Take the remaining 1/4 cup of brown sugar and sprinkle over the top of the ham.
Cook on low for 6-8 hours or high for 4-6 hours, basting with the cooking juices every few hours.
Remove ham from slow cooker and let cool a bit until it can be handled. Slice the ham and serve.
If not serving immediately, preheat the broiler and transfer the ham to a oven-safe baking dish. Brush with some of the leftover liquid and broil for about 5 minutes, glazing with additional liquid as preferred.