There was a school play where an actor forgot his lines. Instead of panicking, he started making up the most hilarious lines on the spot. The whole audience was in stitches. It was a great example of how mistakes can turn into something really funny at school.
One example could be a fanfic where the Survey Corps members play a hilarious prank on Levi. They might swap his cleaning supplies for fake ones that make a mess when he tries to use them.
You can try Archive of Our Own (AO3). It has a large collection of Attack on Titan fanfics, and you can use the search function to specifically look for funny ones by adding relevant tags like 'humor' or 'comedy' along with 'Attack on Titan'.
Perhaps their wedding day was an extremely special moment. It was the day they publicly declared their love and commitment to each other. Another special moment might have been when they overcame a difficult time in their production work together. They supported each other through it, which showed the strength of their relationship.
It's fairly common. Fans often look for more content related to their favorite shows. Since 'Attack on Titan' has a large and passionate fan base, there are a lot of fanfics available. 'Aot' fans might watch (read) these fanfics to explore different scenarios that the official story didn't cover. For example, they might want to see how a certain character would react in a different situation or what would happen if a major plot event had a different outcome.
There could be various fanfictions. Maybe some that focus on alternative endings, like ones where certain characters survive who didn't in the original. For example, a fanfiction where Erwin survives and leads the Scouts in a different way.
Once, my cat chased its own tail for a whole five minutes. It was so confused but also extremely hilarious. It spun around and around until it finally got dizzy and just plopped down on the floor.