Why do girls do this?

Alright. So, yesterday I was in the city, at a park for a celebration with my friend. There was this one guy, the whole time who just followed us around, talked to us. And we talked to him.
  You know, we made conversation, because I was watching my two younger siblings and he was watching his younger cousin, all three of us were stuck at the playground with dozens upon dozens of six yearolds.
 Now, we all have that friend, that one friend who is so fourth grade boy crazy like, and quick to assume that think every guy they meet is into you. Or that every guy you meet is into her. Yeah, this is that friend.

  She insisted that this boy was flirting with me, and, even in the few hours we were there I started to think that maybe he was. I mean, i'm attractive.
  There's that time when you think a boy might be flexing, when you know he's flexing, and that time came. He was flirting. You know, he asked for my number, asked me to Kik him, repeatedly stole my hat from right under my nose. And I wont say he wasn't cute, but what I will say, is I tried my hardest to act as if I didn't think he was cute. As if I wasn't flattered that he was talking to me like this.
  And that's what I wanted to talk about today.
  Why us girls try to act insulted, or disgusted, or too cool to be flirted with when a man or a boy is hitting on us.
  It's like, for me, atleast, like I don't wanted him to think that I didn't want to be flirted with, but I did. I don't know, maybe it's the "play hard to get thing" that I always complain about, telling all my friends how stupid it is.
Maybe it's just implanted in our minds, maybe it's a natural thing that all girls just can't help but do.

Now. I will say this. There is a thin line between being cocky and being arrogant. Flirtatious touching and touching that falls somewhere around sexual abuse, and we all know those guys. Those guys who call out "hey Shawty" and "come hear baby" from the protection of their cars, and the guys who think they can touch you wherever the eff they want to touch you. That's not ok. At all. It's disrespectful and they deserve to be treated in just as disrespectful of a way.
But!
Then, there are those guys who are just, flirting. He's not being nasty, or disrespectful, he's just complementing you. Talking to you. And even if you don't feel like talking with them, they don't deserve to get the cold shoulder. They don't deserve the get lost attitude. And this is coming from a chick who definitely puts of a get lost attitude every once in a while.