For example when the entire chat spams "LUL" emote because something funny happened, you just have to left click at one of the "LULs" sent by users and it automatically gets put into your "Send a Message" box ready to use.

This would make the Chat more active because you dont have to type the entire emote name especially if its an emote you dont know the name of, then you could just click on it and send it, instead of checking the name and typing it.