Shoutbox

Does this automatically pop up or is there key commands to bring it up? Because I really don't want to be interrupted in the middle of something, but I would like to be able to know I have a message (A toast comes up like it usually does when someone messages you for the first time, over the top of the application, and then pressing a certain, rare combination (So that no other applications should pick up that something was pressed), and you can then talk.