Combine brown sugar and cinnamon in a large ziplock bag. Add the pineapple spears, close the bag tightly, and shake it so that the cinnamon and brown sugar coats the spears. Place the pineapple in the refrigerator for at least 30 minutes.
Pre-heat your grill to medium heat, around 350-400 degrees.
Place the pineapple spears on the grill and turn them every few minutes.
Grill the pineapple until it is cooked to your liking.