Term commonly used in conjunction with cheating, playing unfair in FPS or turn-based RTS card games, and hacking or hax0r.
One physical method is to use the standby technique to lag the other players enough to run to a new area before fragmented packets re-capsulate and the other players resume playing. In some cases the players don't notice the transition.
Another method is to run a modified locally cached map that has additions and alterations to the playing field and/or characters/weapons.
#2 Turn-Based and Real-Time Strategy such as Dungeons & Dragons(loose-not officially supported).
(Halo:Combat Evolved) "He disappeared, I was following him around a corner, there was no escape or exit. He just vanished!" "..He must of Ninja Warped!"