The tactic your best friend displayed is known as "provocation." Provocation is a psychological strategy where one person intentionally tries to irritate, anger, or annoy another person to elicit a reaction from them. The goal of the person using provocation is usually to provoke a negative emotional response or to test the other person's limits and boundaries.
In this situation, your best friend was trying to push your buttons by aggravating you to the point of making a threat (telling him you would smack him). By refusing to hit you back, he may have been trying to see how you would react or to assert some form of control over the situation.
It's essential to recognize that provocation is not a healthy or respectful way to interact with others. It can lead to escalated conflicts and damaged relationships. When faced with provocation, it's best to remain calm and assertive, setting boundaries and communicating your feelings in a non-violent manner.
If you find that your best friend's behavior is becoming a pattern and it's negatively impacting your friendship, it may be worth having an honest conversation with him about how his actions make you feel and to establish healthier ways of resolving conflicts in your relationship.