This is activated whenever you receive a MSG from someone. The parameters for the action are as follows:
$0 nickname of person who sent the MSG
$1- The message
Warning: If you attempt to send a msg from within a msg action, it will be automatically converted to a notice, as this will prevent msg loops from being sent between two or more users. Also, you will not be permitted to send either msgs or notices from within a notice action. The irc protocol states that notices may not generate automatic replies so this will prevent loops of automatic messages from flooding the net.