The other night i was out at the bar with some friends. One of my friends brought a girl with him who he was obviously interested in. They had been friends in hs and she is just moving back into the area after college. Me and her started talking and i had no intention at the time of hitting on her, but she made sure to let me know she wasn't interested in the guy that brought her. I didn't get her number that night because i felt it would be disrespectful to my buddy who is a real nice guy. I am, however, interested in the girl. I befriended her on fb and she seemed pretty eager to talk to me.

My Question:
I'd like to take things further with this chick without any awkwardness. Any advice on what would be the best way to get the girls number over fb without it being awkward in any way?

You don't realize this, but getting a phone number is fairly easy.
Chat with her, ask her when she's going to hit the city again and then tell her to give you her number so you can text her where you're hanging out.
Moreover, if she is already interested in you, she will be more than willing to give her number.

Don't think about it too much, just make it come across as something that you do all the time and that you do for logistics-purpose only.

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Game the world.

"what's youre number?"

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"StreetLight!! Stop seeing every problem in life like it's a chick you didn't hit on!"

haha. good points. i've gotta be careful though; i don't wanna upset my buddy. he seems to not know he's in the friend zone

honestly, I'd talk to my friend about it first and see if he's ok with it.
This isnt "pua" advice, its "good friend" advice.
If he understands he doesn't have a chance with the girl, he'll probably give you the O.K. anyways. Pussy is never worth losing friends over.