a) Invented in the popular American television show, the office. It originally was a game where angela, an acountant(and jerk), would count every time the enamored salesman jim left his desk to talk to pam, the secretary.
b)Now, it can mean any instance(work, school, etc.)where one person repeatedly skips out on work to chat it up with his or her "best friend" across the room, and everyone knows there is a thinly veiled crush going on.
a) Angela: I call it "Pam Pong". I count how many times Jim gets up from his desk and goes to reception to talk to you.
Pam: we're friends.
b)person: did you see that new temp? he was totally playing pam pong with erica today.