history: I was super irritated when my boss kept pulling my hair for "fun". He doesnt seem to realize how irritating it can be. I was super irritated when my boss kept pulling my hair for fun! I can see why! That's highly inappropriate.  
current: He seems to think otherwise for some reason. I am thinking about reporting him to the HR.
next: You should. He is obviously at the very least flirting with you and at worst harassing you