Grin, (cool moniker) you know and I know and everybody else knows that this girl thinks you are pretty crushworthy, too. Have you checked out the Squirtonline survey: How to Tell if Someone Likes You? If you want some further squirty yet unsubstantiated psychology-speak, this is why she's acting this way:
Exhibit (a): Peek-a-boo.
I am also guilty of this useless maneuver because I am shy and not very good at all with this flirting stuff I keep hearing so much about. But say the cowboy is, well, a cowboy and what self respecting chick can resist a cowboy? I just can't help myself from gazing at his loveliness...only to die a thousand little deaths when he turns around and sees me...Of course, I repeat the cycle as soon as he looks away. I do not recommend this tactic because cowboys do not understand subtlety and can never figure out whether you like them when you're being all subtle-like. Plus, they don't have to, because not all girls get tongue-tied around lean, strapping young bucks. Er, I digress, but just note that you're the cowboy in this scenario.
Exhibit (b): She's noisy, i.e. showing off.
Young dude, she just wants you to know she's there, I mean, I can't believe I have to spell this out for you. Oh wait, I forgot, you're not a chick. In addition, I'm almost positive she's dressing nicer/sexier for you, and hoping you'll notice when she's being all loud and flirty with other guys. OK, I think I've done this too, when I was in the sixth grade. Does she want to talk to you? Yes. Does she want you to talk to her? Yes. Will she talk to you first? No. She's got all these other guys to flirt with, which brings me to...
Exhibit (c): Flirty Town, USA.
Same as above, except she's also saying, "See how cute I am! See how cute I am flirting with other guys! P.S. Will you please ask me out so I can stop talking to all these palookas?" The good news, G, is that she really wants to flirt with you, except that she's too shy because she likes you better and what if you don't like her back? Ugh, messy rejection, cruel disappointment, life sucks! Ow. Just the fact that this vixen is not flirting with you is a big giveaway. It's a whole lot safer to flirt with guys when you rub out the rejection factor. (Not that there's anything wrong with flirting, but just because someone is flirting doesn't necessarily mean they want anything more than...attention. Yeah, I know, flirty people are weird). So how can you tell whether someone who flirts with you not only likes you (a given), but madly, truly, deeply digs you (not given)? Um, tough call. If she's got a boyfriend already, she's just having fun at your expense. If, say, I'm flirting with you, I'm probably desperately in love with you...but I can't speak for everyone.
Would it make more sense if she just talked to you if she likes you so much? Of course, but she won't, because she likes you so much. Trust me, though, exhibits A + B + C = go ask her out already, and let me know what happens.
I do feel obligated to mention that there is the smallest possibility that she knows you dig her and is just messing with your head. But so what? You'll never know unless you ask her out. Go for it, G!
Hugs and kisses,