Nothing But Clay couch gag

This is the first and only appearance of Gumby on The Simpsons.

Plot
The living room is made of clay. 6 balls roll all over the house. Then, the characters emerge from the balls (Homer, Marge, Maggie, Lisa, Bart and Gumby) and sit on the couch. Later, Gumby waves at the family before it cuts to the TV scene.