So I was at a party last weekend and some girl came right up to me and said:
Her: That shirt looks really good on you
Me: Every shirt looks good on me (jokingly)
Her: *she laughed* My boyfriend is right over there (she points to him but he was not looking)
Me: Thats great

Then she instantly gave me the cold shoulder and walked away. I was really thrown off by this considering she was the one who just walked up on me. Does anybody have any idea of what might have went wrong, cause honestly she was at least a HB8.

That is a total WTF moment. Why the hell did she bother approaching you just to point out her bf?
Maybe she wanted to challenge you to see if you had the balls to steal her away from underneath her bf's nose

THAT

Or they were swingers and wanted a third hahaha

maybe she is this weird person who points random people at parties and says "he's my boyfriend"

LOL! WTF?!?

or maybe.. she really wanted you to know that your shirt looks good on you.
maybe she is a stylist or something and felt the urge to let you know you are dressed well...

anyways.. wear this shirt more often. it is your lucky shirt from now on.

Mike.

haha yeah I gotta say this is the second compliment from a girl that I got about this shirt except the first one was not as random as this one.

Regardless of what did happen this encounter do you think it was a good call going for the jokingly cocky remarks or should I just more or less thank them for the compliment

I think the best way to go (though after thinking... RESPECT if you can adlib like that on the spot)

Her: That shirt looks really good on you
You: Thanks! What are you a stylist?! (delivered in a cocky way[like you like. hehe])


either:
Her: Yes actually! I am
You: Oh cool!... bla bla bla bla (making conversation)

OR
Her: No... i just...
You: (don't let her speak) and say.. "naaa... i'm just kidding, i got this shirt at X's, you know, they the weirdest thing there bla bla blablabl (making conversation)


BUT IT CAN ALSO BE:
Her: *she laughed* My boyfriend is right over there (she points to him but he was not looking)


You can't win every frame....


Good luck..

Mike.