Flirt with them the way your flirting with and opposite sex
She may be bi-curious
Carefully.
Yes. Unless your girlfriend is bisexual, and her best friend is bisexual or gay.
Flirt! : )
Anything and everything you would do with a straight or gay friend.
flirt with him some more and kill your friend
you dont, this could cause problems between you and your friend
If this person is truly your best friend, you should be ok with them knowing so go ahead and flirt! XD
you ask them.
learn to flirt
Flirt
The same as you should do if you were heterosexual and your friend was of the opposite gender, focus on your friendship and be a good friend.