Answer:
Hand shaking because of inertia (1st Law).
Step-by-step explanation:
We shake our hands to get rid of the drops. Newton's 1st Law tells us that every object will continue its state of rest or movement until a force is applied. This property is called inertia. When we shake our hand we impart a velocity to the drops, and then we suddenly change the direction our hands are moving, while the drops continue on their previous trajectory, leaving our hands. If we do it slowly it won't work because other forces would have plenty of time to act and keep the drops in our hands.