I just walked today - got an MFA in illustration - did this in my sketchbook at the ceremony. Someone next to me said "do a self-portrait" and I whipped this out.
I've played lots of roles in my own comics, from narrator to hero, to victim, to keeper of order, to bringer of chaos. I even had a cartoon cameo in a web 'toon. Great times, great times!!! I guess it's pretty standard fare for a cartoonist to put himself in the picture so people can see the world as he sees it.