A very special form of
irc lag. Usually when you have a huge laggy
IRC network, you can expect to get some kind of
lag-- i.e. you'll have two servers lagged to each other, and anything people on the first server say will take 30 seconds or so to reach the people on the second server and vice versa.
This is irritating, but not nearly so irritating as the dreaded netburst, which is what happens when instead of sending the comments in a desynched but steady flow of 30 seconds ago, the lagged server chooses to send nothing for 30 seconds and then dump all 30 seconds of comments all at once. Netbursts often strike wholly without warning, so you'll have a conversation of several people, and suddenly half of them will go rather silent; confused, the conversation continues, and then WHAM, 20 or so comments, some related to your conversation or in blind response to things you said in those 30 seconds, some not, flood the screen and push what you were saying off.
If netbursting ever becomes heavy, intelligent conversation becomes pretty much impossible.