First, I will let him know that he is doing something that is not allowed , and its disrespecting. If he didn't know its not allowed I will warn him anyway for disrespecting, and I will tell him about the rules, and I will tell him to type !motd to see the rules to prevent this from happening again. then , I will check why did he disrespect, maybe there is a valid reason for that ( I'm afraid there is no valid reason for disrespecting , tho.).