rcirc-response-formats

rcirc-response-formats is a variable defined in `rcirc.el'.
Its value is

(("PRIVMSG" . "<%N> %m")
 ("NOTICE" . "-%N- %m")
 ("ACTION" . "[%N %m]")
 ("COMMAND" . "%m")
 ("ERROR" . "%fw!!! %m")
 (t . "%fp*** %fs%n %r %m"))

Documentation:
An alist of formats used for printing responses.
The format is looked up using the response-type as a key;
if no match is found, the default entry (with a key of `t') is used.

The entry's value part should be a string, which is inserted with
the of the following escape sequences replaced by the described values:

%m The message text
%n The sender's nick
%N The sender's nick (with face `rcirc-my-nick' or `rcirc-other-nick')
%r The response-type
%t The target
%fw Following text uses the face `font-lock-warning-face'
%fp Following text uses the face `rcirc-server-prefix'
%fs Following text uses the face `rcirc-server'
%f[FACE] Following text uses the face FACE
%f- Following text uses the default face
%% A literal `%' character

You can customize this variable.