Anytime you look through the friends of YOUR facebook friends for anyone you may know. Specifically to add anyone that is already NOT your friend. In other words a lazy approach to finding people by using the existing work of others.
I was 'friend poaching' the other night on facebook. I found three people I went to high school with when I searched through my friend Alex's facebook friends.
The act, usually committed on facebook, of adding a friend of your friend, whom you have never previously met or come into contact with. Upon acceptance, the friend poacher usually makes over exuberantly friendly and all too awkward comments on his new "friend's" statuses.
dude 1: Hey, it says that we have (insert name) as a mutual friend, how do you know him????
dude 2: ... uhh...
dude 1: dude have you been friend poaching???? Stop poaching my friends bro.