They are hired for a kid's birthday party. A fancy woman, Ms. Mildred, asks them if they are her caterers, which Mr. Krabs confirms. It ends up being pandemonium.
It starts when the birthday kid from the party keeps on following Mr. Krabs, yelling "I want my birthday cake!" Then, SpongeBob makes the Krabby Patty into a fancy dish called the "Krabby Pâté" and Patrick eats it. Patrick soon starts eating everyone's patties. Then, Squidward sees a clarinet player and takes over, and starts playing off-key. Meanwhile, Mr. Krabs is trying to return the jewels that SpongeBob used to make the Krabby Patties fancy. He finds a room with a giant water bed, as the birthday kid is jumping on it.
Mr. Krabs pops the bed while trying to get him off. The water splatters everywhere, wrecking the building.
Mr. Krabs claims he is off to make a delivery and a patty falls out of the Krusty Katering truck.