The rock balloon is a balloon that appears in the episode "Krusty Katering."
It is made out of multiple balloons and is purple, magenta, light green, red, and yellow. It is lumpy and anyone who holds it will automatically fly away.
Role in episode
When a child at the birthday party wants a balloon, Patrick has to think fast. He decides to make a rock balloon and then gives it to the kid, who, after holding the balloon, immediately flies away with it for the rest of the episode.