To celebrate his Sunday, SpongeBob makes a sundae using odd ingredients because he does not have any ice cream left and finds bananas and cherries to be boring. After using ketchup and onions, he decides that he wants to put peanuts in it. However, he does not have anymore, so he uses the peanut plant sitting on his bathroom windowsill. Afterwards, he finally eats the sundae, giving him rancid breath.
SpongeBob goes downtown to say hi to people, but everyone in Bikini Bottom avoids him, excluding Patrick because he does not have a nose. Since SpongeBob does not realize that everyone is avoiding him because of his breath, Patrick suggests that it is because he is ugly, and he assumes that.
Later in the episode, Patrick tries some of the sundae, causing SpongeBob to realize that it gives them both rancid breath and that is why everyone was avoiding him.
Role in Stinky Swagger
SpongeBob must collect peanut onion sundaes in order to keep his bad breath.
In Battle for Bikini Bottom, the sundae was originally going to be used as a power-up that would allow SpongeBob and Patrick to run faster and destroy stone tikis. However, this was scrapped before the game's official release.