Desync
A desync is where two or more computers in a synchronized multiplayer game (such as Duke) stop behaving in the same way.
Going out of sync can be caused by problems with EDuke con code (prior to EDuke there was insufficient power in con to do it), by bugs in the game source, by different con map or art files on the systems in the game. by network conditions or by insufficient computing power on one of the peers in the game.
Duke detects certain types of desync and gives the message "OUT OF SYNC PLEASE RESTART GAME." however other types of desync could be exploited with great care to make different players see different things.