Usually used in conjuction with a game such as Counter-Strike. When a group of friends either on LAN or using an online voice communcator (ie. vent or teamspeak) go in and basically mess around and screw up the server.
Such as going into a 1.6 server, buying all shields and making a wall that no one can get past. Or trapping people with shields. Also stuff that the pubmasters have done on their video.
Named after Jev because he does some stupid things =D