Prepare a skillet with enough vegetable oil to fill it about an inch deep. In a flat bowl, mix sugar and cinnamon. Unwrap biscuits and cut out a circle from the center of each using a melon-baller or spoon.
Heat oil in the skillet on medium-high heat. Fry donuts in batches, turning when lightly browned, for about 2-3 minutes per side. Immediately coat each donut in the cinnamon-sugar mixture and set aside. Repeat for remaining donuts and holes. Serve warm and enjoy!