IRC
From Hackepedia
You've probably been sent here for making a booboo on Internet Relay Chat (IRC).
IRC:1 Search first, ask last.
IRC:2 U.S. Politics
IRC:3 Asking to ask
IRC:4 Wrong channel
IRC:5 LART
IRC:6 Search that question/term
IRC:7 Don't private message a stranger
IRC:8 Long URL
Clients
For UBOs: xchat is the most popular GUI client. Some ncurses based clients are: irssi epic BitchX
For Windows: Mirc is by far the most popular. Perch is another example.