Log on, pick a character, go back to the character select screen and stay there for an hour/overnight/for a week/for a month. When you get back on, you'll be flooded with all the friends lists messages you get, like people talking to you, people joining games etc.
I thought it was pretty cool that once you get back on, all the messages would scroll. If you've got a lot, they can keep scrolling for a while. It's not sudden.