Planet ZK-5 was a ringed planet in the farthest reaches of the galaxy. It was inadvertantly visited by Spaceman Spiff when he was attacked by Muck Monsters of Mordo and crashed into the icy, rocky rings causing him to plummet to the surface below.
Counterpart
ZK-5's rings were actually dodgeballs thrown at Calvin in gym class by Moe and another bully.