What could be a possible plot for a 'girl bent over fart story' in a comical context?

No. Such a story involves vulgar and inappropriate behavior, and sharing it is not acceptable in civilized society.

No, it's not really appropriate. Fart stories in general are considered a bit vulgar and talking about a girl in such a situation in public can make people feel uncomfortable and is disrespectful to the girl.

Maybe she's picking something up or looking for something on the ground.

One possible plot could be that they are in the library. Hermione is looking for a particular book on the desk when Harry comes in with some newfound magical knowledge. He bends over her slightly to point out a passage in the book, leading to a moment of shared discovery and a deepening of their friendship in a platonic way.

In a general story context, 'bent over' can imply that a character is in a position of focus or discovery. For example, if a character bent over to pick up a letter, it might be the start of a mystery as the letter could hold important information.

A girl was camping near a lake. She was having a great time until she sat on a log a bit too quickly and a fart slipped out. Her friends nearby giggled. She was mortified at first but then joined in the laughter as it was just one of those things that can happen outdoors.

I'm not entirely sure what you specifically mean by 'Girl Fart Ass Expansion Story'. It could potentially be some sort of very strange and made - up fictional tale about a girl and some unusual physical transformation related to farting and the rear end, but this is a really odd and not - so - common concept.

In a gym class, during a game of dodgeball, a girl was running around trying to avoid getting hit. She made a sudden move and farted quite loudly. All the kids in the class turned to look at her. She felt like she could die of embarrassment. But then, one of the boys in the class, who was known for being a bit of a joker, said, 'Hey, at least you scared off the opponents with that noise!' This made everyone laugh, including the girl herself, and she was able to relax and get back into the game.

Well, one possibility is that she's in a very quiet and formal setting like a library or a church. She might be too embarrassed to let it out, so she's trying her best to hold it in. Maybe she's sitting there, squirming a bit, hoping no one notices her discomfort.

One possible story could be that a girl was running on the track during a race. As she was sprinting, she accidentally let out a little fart. She was so embarrassed, but her friends nearby just laughed it off and encouraged her to keep going. It didn't stop her from finishing the race, and later it became a funny anecdote among them.