There could be several reasons. Firstly, it could be a sign of a very unbalanced power dynamic in the friendship. The friend who spanks might feel superior in some way. Secondly, it could be part of a fictional world where the rules of normal behavior are distorted. Maybe the story is set in a place where there are strange social norms. Thirdly, it could be due to a major conflict or betrayal in the story. The spanking could be an extreme reaction to a perceived great wrong, but still, it's an inappropriate way to handle things in a friendship.
One possible reason could be a misunderstanding. Maybe the friend thought the girl had done something wrong that affected them directly, but instead of talking it out, they resorted to spanking out of anger or impulse. Another reason could be in a story set in a different cultural or historical context where physical discipline was more common among peers, although this is not common in modern friendships.
One possible reason could be that they had an argument over something important to them, like a shared toy or a secret that was spilled. And in the heat of the moment, the friend lost control and spanked the girl as an extreme reaction.
Maybe in the story the girl sees it as a form of attention. Sometimes children might misinterpret discipline as a way to get their parents' focused attention. If the mom is often busy, the girl could think that getting spanked, which is a form of interaction, means her mom is paying attention to her.
One reason could be for a joke or a dare. Friends often do crazy things like this just to have a laugh. Another reason might be that your friend is curious about how the opposite gender dresses and wants to experiment through you. It could also be part of a prank for a special occasion like a birthday or an April Fool's Day.
One possible reason could be that the children have misbehaved seriously. For example, if they have been repeatedly disobedient, like not doing their chores or constantly getting into fights with each other. Another reason might be that they have broken some important family rules, such as lying or stealing. Mothers often use spanking as a last resort when other forms of discipline, like talking or grounding, haven't worked.
One possible reason could be a need for attention. Sometimes children act out in unusual ways to get their parents to focus on them. If the girl feels neglected, she might think that this extreme behavior will make her mom pay more attention.
One possible reason could be that the boy misbehaved at school. For example, he might have been bullying other kids, which is unacceptable behavior. His mom spanked him to teach him that such actions are wrong.
One reason could be for fun. Friends often do crazy things just to have a good laugh together. Another might be for a bet or a dare. Maybe they lost a bet and had to do this as a punishment. Or it could be part of a creative project, like making a funny video or a photo series.
Maybe the mother lost her temper and couldn't control her emotions at that moment. She might have been very angry about something the girl did immediately.
No, it's not acceptable. Friends are supposed to support and respect each other. Spanking is a form of physical punishment that is inappropriate in a friendship. A healthy friendship is based on equality, mutual respect, and positive interactions. If there's a problem between friends, they should use dialogue and negotiation to solve it, not physical actions like spanking.
It could be that she was trying to break the ice if there was some sort of tension or awkwardness between them. For example, if they had a small argument earlier, tickling could be a way to show that she still cares and wants to have fun together. Also, it might be a spontaneous act of playfulness. If they were in a boring situation, like waiting for something, tickling would add some excitement and fun to the moment.