Shaking after a roller coaster is a physical reaction known as an "Adrenaline Dump" or an "Adrenaline Shiver." When you experience the intense drops and high G-forces of a coaster, your body’s "fight or flight" response is triggered, causing the adrenal glands to flood your bloodstream with epinephrine (adrenaline) and cortisol. This increases your heart rate, sharpens your senses, and sends a burst of energy to your muscles to prepare for a perceived threat. Once the ride ends and your brain realizes you are safe, the "emergency" signal stops, but the excess adrenaline is still circulating in your system. The shaking is your body’s way of "burning off" that unused energy and processing the rapid physiological changes. It can also be a result of a sudden drop in blood sugar or the physical strain of "bracing" your muscles against the coaster's forces. Drinking water and taking a few slow, deep breaths will usually help the tremors subside within 10 to 15 minutes.