Smiley face

I've noticed recently the little box next to the drop down menu on the upper right has switched to a smiley face.
The smiley face also appears next to the user name in some places.
Is there a way to change this?
Sorry, flashbacks to the graphic novels many years ago with demonic smiley faces....

Upload a picture in your profile, ya cube-head!

I kept looking in the Shop stuff to do this and couldn't find it.
DOH!