When an introduction of a conquest and/or person of interest takes place in a social setting, and to clarify the person you are introducing them you are currently hooking up or intend to hook up with the person you are introducing to another friend. When stated "My friend", you imply that the person you are introducing is fair game to make a move on.
When stated "Your friend" means she is spoken for and YOU may not, make a move on, and should respect that YOU have plans in place and/or have already done enough ground work to seal the deal.
Warning: Buddies that violate the rules of My Friend Your Friend, may be subject to multiple cock blocking, harassment, ridicule and organized swooping by other buddies...
Habitual violators may earn the dishonorable title Harbor Shark see additional definition
Buddies are welcome to sleep with "My Friends" but not "Your friends"
Hey Dave, This is my friend Bertha. (Buddy system code for she is fair game)
Hey Dave, This is your friend Trixie. (Buddy system code for I'm already on it and want it... don't harbor shark me)