The guy might get an idea in a cartoon when he accidentally stumbles upon something or when he's reflecting on past experiences. It could also happen when he's observing the actions of others and it makes him think differently.
Well, it could be that the guy gets all nervous and starts acting weird around the girl he likes. Maybe he stumbles over his words or blushes a lot.
He might be trying to escape from something dangerous inside the hole, like a monster or a trap.
They could be working on a project together, maybe collaborating on a business deal or presentation.
Maybe he's in a crazy race and lost control. Or he could be trying to show off and ended up crashing through the window.
In some 'goku gets hurt fanfiction', he might get hurt while protecting his friends or family. For example, he could take a fatal blow meant for someone else. This would not only physically harm him but also add an emotional aspect to the story as his loved ones would be worried and try to save him.
In the fanfiction, perhaps Loki's sickness is a result of some magical backlash. As he gets sicker, he could start having strange visions or nightmares that are related to his past misdeeds. His loyal followers might then try to find a cure for him, leading to an adventure to seek out a powerful healer.
Well, in some fanfictions of this kind, Naruto could be tortured physically by being chained up and beaten. His captors might also starve him or deprive him of water to weaken him. It could also be that they use some sort of dark magic or forbidden techniques on him that cause extreme pain and discomfort.
Well, perhaps in the fanfiction, Goku gets mad when he discovers that someone has been using his name for evil deeds. This would go against his values of justice and protecting the innocent. He might get really angry and go on a search to clear his name and stop the impostor. Or it could be that a new, extremely powerful villain emerges and starts to destroy planets without any remorse. Goku, being the defender of the universe, would be enraged by such senseless destruction and would confront the villain with all his might.
One possible scenario could be that he is killed in a lightsaber duel by a powerful Sith opponent. Maybe this new Sith has some secret technique that Anakin couldn't counter.
In this fanfiction, perhaps John catches a mysterious illness that has strange symptoms. It could be a magical malady in a fantasy setting, like a curse that makes him age rapidly.