Heat vegetable oil in a skillet, about 1/2 inch deep, over medium-high heat. Roll out and separate crescent roll dough. Mix sugar and cinnamon in an 8x8 dish.
Check oil readiness by adding a pinch of flour – if it bubbles, it's ready. Lower heat to medium, add dough triangles with space in between. Cook about a minute on each side until golden brown. Transfer to paper-towel-lined plate.