http://www.usatoday.com/life/2004-03-25-coming-attractions_x.htm
After 15 seasons of The Simpsons, creator Matt Groening
finally gets a guest spot (Fox, April 4, 8 p.m. ET/PT).
"The writers wrote it in as a goof. I thought, 'I'll show them.
I'll do it,' " he says. He has supplied a couple of sounds - Maggie's pacifier, a
Ned Flanders scream - but this time Groening plays himself.
He's identified as the creator of Futurama. (He couldn't be the
creator of The Simpsons on The Simpsons or "the whole universe
would implode.") Though Groening didn't draw his picture, it's
closer to real life than one earlier depiction as "an eyepatch-wearing,
head-shaved, right-wing gun nut."He's wrong about the universe-imploding thing though. "The Simpsons" popped up as a show on "Futurama," so now he's appearing on a show as the creator of another show that references a show he appeared on as the creator of a show that references a show he appeared on as the creator of a show that references a show....
And so on.
-Jay