Having one's anus forcefully, repeatedly and not-always-voluntarily resized. Size 9ing is most often performed courtesy of one's new cellmate's johnson, although at some parties, a proper piss-on / pass-out may elicit the act.
Guy 1: "Why is Shiela walking all funny?"
Guy 2: "She got Size 9'ed after passing out face down on the couch at Bob's party."
Guy 2: "She got Size 9'ed after passing out face down on the couch at Bob's party."
by The Evil Steve August 5, 2005