flood
On a real-time network (whether at the level of TCP/IP, or at the level of, say, IRC), to send a huge amount of data to another user (or a group of users, in a channel) in an attempt to annoy him, lock his terminal, or to overflow his network buffer and thus lose his network connection.
The basic principles of flooding are that you should have better network bandwidth than the person you're trying to flood, and that what you do to flood them (e.g., generate ping requests) should be *less* resource-expensive for your machine to produce than for the victim's machine to deal with. There is also the corrolary that you should avoid being caught.
Failure to follow these principles regularly produces hilarious results, e.g., an IRC user flooding himself off the network while his intended victim is unharmed, the attacker's flood attempt being detected, and him being banned from the network in semi-perpetuity.