If you want to add or remove the words that are filtered in your server. Go to base\config\server\prefs.cs.
Line 10: $Pref::Server::CurseList = "[Edited out for obvious reasons]";
Line 12: $Pref::Server::ETardList = " u , r , ur , wat , wut , wuts , wit , dat , loel , y ,";
Just add or remove words, separated by comas, of course.
You can also disable it in: Start A Game > Advanced Config. > Uncheck the desired filter(s).
Or in base\config\server\prefs.cs
Or do it in the console:
$Pref::Server::CurseFilter = 1;
$Pref::Server::ETardFilter = "1";
Change the 1 to a 0 to disable it.
[Edit] - Make sure your game is shut down before you edit the prefs.cs file, otherwise when you close the game it'll reset to the setting at point of game start. If you want to edit with game running, just put the commands in the game console.