Boomerang Pet Ball
The Boomerang Pet Ball is a toy that SpongeBob bought for Gary in the episode Gary Takes a Bath. It made its only appearance in that episode.
Design on the box
It says "New Boomerang Pet Ball. Really Works". It is a small box that just fits the ball.
What it does
The ball is supposed to "boomerang" off things or in mid-air. The box also boomerangs off things, which then hit SpongeBob in the face. It is repelled back to the thrower when thrown.