WALL [<channel>] <message>
The channel and the message; if no channel is given, the active channel will be used.
Sends a message to all channel operators. If the server doesn’t support WALLCHOPS or STATUSMSG it will send a notice to each channel operator individually.
/WALL I'm off for today; take care! :) /WALL #irssi I'm feeling supercalifragilisticexpialidocious today :D