"Ooh! Patrick has too many balloons. He has oodles of zoo balloons."
SpongeBob and Patrick are at the zoo. Patrick wants a balloon, so SpongeBob buys one for him. Then Patrick sees a balloon that looks just like the dolphin he and SpongeBob saw in the blue lagoon; he buys that one as well. He buys even more balloons and Patrick still wants more even when there are too many on his arms. This causes Patrick to fly into the air, calling for help to get him back to the ground.
To help save Patrick, a spiky fish gives SpongeBob three of his spines to pop the balloons. SpongeBob puts the spines into the straw of the juice box he was drinking and blows through the straw, directly aiming at Patrick. All of the balloons pop and Patrick is finally saved, but the balloons took Patrick too close to the sea lions' pool, one of them wanting to play with him. So, SpongeBob throws a loop around Patrick, but lands him into the pool by accident.
The book ends with SpongeBob agreeing to buy another balloon for Patrick, but just one to avoid the same trouble that occurred previously.