Also a term used by the "B:\" hacking gang as like "secret handshake".
(Note: the jock usually responds with a "stock" insult IE: "your mum" "fuck you" "you are a idiot" and then slumps off to see his girlfriend, which incidentally have never seen each other in their lives, talked for 10 minutes and are now kissing and hugging)
B:\ Hacker: Pac.
Other hacker (not bdrive): Whaa?
Other B:\ Hacker: *nods discretely*