Feels nice. When I had long hair my gal pals would always ask to braid it, so they would tug and sometimes it kinda hurt but it still felt nice, put me in a sort of daze. I miss that now that I have short hair, but since cutting it ive noticed that it's ridiculously soft and silky, and if a guy were to pull on it, I would enjoy that because I know he would notice how nice it is, and also because the tug of it feels good, the same way it used to when girls would braid it. Hair is an extremely strong sexual symbol. Healthy hair displays fertility/potency, (even if you're not trying to have a baby these things still matter. Society has advanced far too quickly for our instincts) so a man recognizing that a woman has good hair is going to have an increased libido, and a woman being aware that her hair is being appreciated is going to have a confidence boost. Its like tugging on a cat's tail as you're stroking it- just pulling wouldn't feel nice, but the cat enjoys it if you do it right.