v. when, in a college dormitory bathroom or other communal restroom facility, all of the shower stalls are occupied, and an individual who is short on time (or manners) strips off his clothes and runs into a random stall, gleefully yelling, "showerjack!" and forcing the former occupant out.
n. an instance of the above maneuver.
"Dude!? What the %^&* is wrong with you?"
2) "That was a nasty showerjack; I'm going to go soak his underwear in capsaicin."