ctcp <target> echo <any text>
This CTCP request asks the other client to return your message back to you. Tricks like this were formerly the way that PING times were measured. Many clients do not support this request because attacks by floodnets can disconnect you from your irc server.
# $EPIC: ctcp_echo.txt,v 1.3 2006/07/24 19:50:14 sthalik Exp $