What could be the psychological reasons behind a girl pooping herself in fear in such a story?

One reason could be extreme stress. Fear can cause the body to go into a fight - or - flight response, and sometimes the body's normal functions can be disrupted, including bowel control. Another might be a lack of proper coping mechanisms for intense fear.

Maybe she was under extreme stress or fear. Stress can have a physical impact on the body and disrupt normal bodily functions. For example, if she was in a very scary situation like being chased, her body might go into a fight - or - flight response and this could potentially lead to such an accident.

One reason could be that she was too engaged in an activity, like the girl on the swings. She was having so much fun that she didn't pay attention to her body's needs. Another reason might be a lack of access to a toilet, like the girl on the long car journey. There was nowhere to go so she had no choice. Also, being distracted by excitement, such as at the school event, can make a girl forget about the urge until it's too late.

One reason could be that she had a sudden and severe stomach illness. Maybe she ate something bad before getting in the car and couldn't hold it any longer. Another possibility is that she was too young to control her bowel movements properly and there was no toilet available in time while in the car.

No, such stories are not very common in mainstream literature. Most literature focuses on more positive or complex emotions and situations rather than this rather extreme and embarrassing one.

Once there was a little girl named Lily. She was so engrossed in playing on the swings at the park that she ignored the urge to go to the toilet. As she continued to play, suddenly she couldn't hold it any longer and had an accident. She was very embarrassed but her friends were kind and helped her clean up. They told her it could happen to anyone.

Well, it could be a form of creating a sense of the abnormal or the extreme. By coming up with such a story, it grabs people's attention. Also, in some cases, it might be a way to spread rumors or make fun of someone in a very mean - spirited way. However, this is not acceptable behavior. In a more general sense, it might also be an example of how people sometimes create stories around embarrassing or taboo topics just to break the social norms in a story - telling context.

Maybe she was playing too hard and ignored the urge to go to the toilet for a long time. Kids often get so engrossed in their play that they forget about their bodily needs until it's too late. Also, it could be that there was some kind of problem with the toilets around her. For instance, if all the nearby public toilets were locked or out of order and she couldn't hold it any longer.

Maybe she had a sudden stomachache and couldn't hold it any longer. For example, she might have eaten something bad before getting in the car.

One reason could be a weak bladder sphincter. If it's not strong enough, the pressure from laughing during tickling might cause involuntary urination. Another possibility is that she has a very sensitive nervous system, and the tickling stimulates the nerves in a way that disrupts the normal control of the bladder.