A chronic lagger; especially in an online game such as Warcraft III. Usually having to do with the likelihood that the lagger is using a dial-up connection (56k or less) and may also be downloading music or something while playing the game, thereby taxing the connection beyond all reasonableness. Hence: modem PULLER.
Coined by scron on battle.net
That guy is such a modem-puller, he lags the game so much.