It might also be that Spongebob has made a series of small mistakes that have piled up over time. In the fan fiction, he could keep forgetting to do simple things like his job at the Krusty Krab properly, or he's always late for important meetings. This cumulative effect of his carelessness could lead to everyone getting frustrated and mad at him.
He might be really confused at first. Spongebob is often naive, so he may not immediately understand why everyone is angry. He could just keep smiling and asking what's wrong in his innocent way.
One reason could be ChiChi's overbearing nature. She is often very strict about Goku's training and how he spends his time. In fanfiction, this could be exaggerated to the point where Goku finally gets fed up. For example, if she constantly nags him about not doing enough chores around the house instead of training, it might push Goku to his limit.
Obviously, Spongebob himself could be a main character. He could be on a quest to find the perfect lemon for his grandmother's lemon pie recipe. Patrick could also be a main character, tagging along with Spongebob and providing his own brand of silly commentary throughout the adventure.
It could be that Ron's actions were causing problems within the Order of the Phoenix. If Ron was being stubborn and not following the plans or orders set by the Order, which Sirius is a part of, Sirius might get angry. He would be frustrated with Ron for not being a team player and potentially endangering the mission and the lives of others.
One common theme is friendship. Just like in the original show, in the fan fictions, Spongebob's friendships play a big role. His friends often help him in his superhero adventures. Another theme is protecting Bikini Bottom. The town is always in some sort of danger and Spongebob, as a superhero, has to save it.
I'm not sure specifically as there could be many different plots in various fan fictions. It might involve Spongebob being exiled from Bikini Bottom for some misdeed or misunderstanding. Maybe he has to survive in a new and strange place and learn valuable lessons along the way.
In a fanfiction scenario, perhaps Plankton frames SpongeBob for stealing the Krabby Patty secret formula, which gets him fired. SpongeBob then goes on an adventure to clear his name. Along the way, he meets new friends in other parts of the ocean who help him prove his innocence and he returns to the Krusty Krab triumphant.
Mr. Krabs would probably be thinking about how this could be good for business. He might see it as an opportunity to create a new tourist attraction. Patrick would be really happy for Spongebob at first, but then he might get a bit jealous because he doesn't want to lose his best friend. Squidward would be extremely annoyed by all the commotion and the fact that he has to be part of the wedding in some way.
There might be some out there. With the vast world of the internet and the creativity of fans, it's possible that someone has created fan art of this odd combination. You could try searching on popular fan art websites or social media platforms dedicated to either Spongebob or Pulp Fiction.
Ethically, 'Spongebob sexual fan fiction' is completely unacceptable. It distorts the original meaning and purpose of the Spongebob character. Spongebob is designed to bring joy and laughter to children and families. By creating sexual fan fiction, it perverts that intention. Moreover, it can lead to a bad reputation for the Spongebob franchise and make it seem less family - friendly. It also shows a lack of respect for the values that the show represents, such as friendship, fun, and positive values.