There is no malice in your son's behavior. He shouldn't be punished, just redirected. Here's what's going on.
At this age, your son feels emotions intensely. But he does not yet have the verbal skills to put his emotions into words. Instead, he shares them with you by using his hands. (Other preschoolers kick or bite in this situation for the same reasons.) This behavior will go away as soon as his ability to use words catches up with his ability to feel.
You can help this process in several ways. When you see that he's excited, use words that help him identify his emotions. ("I can see that you're very happy when the choir is singing!" "I know that you're angry that you have to go to bed right now.") This will help him learn which words describe what he's feeling.
Also, you can guide his enthusiasm in other directions that let him express himself physically. When he sees dancing on television, show him how he can join in. When he's happy, have him practice giving you a big hug and a kiss. And while you're at it, give him one back!
