It is the default avatar for all users. We use Justin Bieber's face to encourage people to change their avatars to something less annoying.
Once you're logged in, all you need to do is click on your avatar and select the desired image on your hard drive. Keep in mind the image will be resized to 50x50 pixels.
Use the "Report this post" button to report any post that is breaking the rules. We will review all reported messages and ban anyone too naughty. If you feel reporting isn't enough, feel free to email us with any complaints / suggestions.