It is more convenient to use a shake cup, because protein powder is not easy to stir evenly. If you stir a stick with a spoon or something, it will basically agglomerate and a pile of powder in your mouth will not be absorbed well. Not the same as a milkshake cup. For example, I usually use the American Condi Kelong shake cup. There is a mixing ball in the cup. Pour in protein powder and water. Just pick up the cup and shake it a few times. The stirred protein powder is particularly delicate and smooth, tastes super good and is easy to absorb, so many people in the gym will use shaking cups.