One reason could be cultural. As I mentioned before, in certain cultures like those in parts of Europe, kissing on the cheek is a common greeting among friends, regardless of gender. So male best friends might do it as a normal part of their cultural interaction.
Well, in some cultures, a friendly peck on the cheek between male best friends is quite common. For example, in France, it's a normal form of greeting among friends. I once knew two guys who were best friends since childhood. When one of them got married, the other gave him a big hug and a quick peck on the cheek as a sign of their deep friendship and celebration of the big day.
There's a story of two female friends, Anna and Emma. Emma was going through a bad breakup. Anna took her on a road trip across the country. During the trip, they talked, laughed, and Emma slowly healed. It was a story of how a friend can be there in the toughest of times.
In some stories, it might be for the sake of establishing a hierarchy. Boys may try to show who is more dominant by spanking each other. It could also be a form of initiation in some fictional school cliques. They use spanking as a way to test new members or to prove loyalty. Sometimes, it could be a simple result of immaturity. High - school students are still growing and learning, and they might not fully understand the inappropriateness of such actions and do it for fun without realizing the consequences.
It could be a big fight or misunderstanding. Maybe one friend did something that really hurt the other's feelings.
For fun. Young people are often adventurous and like to try new things. Crossdressing can be a really exciting and different experience.
Hurt pride is another reason. When a friend makes fun of or humiliates another friend in public, the humiliated friend might want revenge to restore their pride. Let's say a friend laughs at another's appearance in front of a group. The one who was laughed at might then try to get back at the other by revealing an embarrassing secret. Also, feelings of betrayal play a role. If a friend breaks a promise or shares a secret that was supposed to be kept, the wronged friend may seek revenge as a way to cope with the pain of the betrayal. They might distance themselves and also start talking badly about the betrayer to mutual friends.
One reason could be a sudden rush of strong emotions. For example, if you've been through a lot together and there's a deep sense of loyalty and love, it might lead to a kiss. It doesn't have to be romantic love, but just a very intense platonic love.
Well, it could be that they have developed a really deep emotional bond over time that has a sexual undertone they only just realized. Or perhaps they were in a situation where they were feeling lonely and sought comfort from each other in a more physical way. It could also be part of a phase of self - discovery where they are exploring their sexuality.
They could fight over a shared resource. Say they both want to use a car they co - own at the same time. Or perhaps it's about loyalty. If one friend feels that the other has been more friendly with someone else and has neglected their friendship, it can start a fight. Sometimes it's just stress. If one or both friends are going through a tough time like problems at work or family issues, they might take it out on each other and start a fight.
Perhaps they are exploring their own identities or boundaries. In modern society, people are more open to different forms of relationships and expressions of love. They might be in a situation where they are trying to understand the nature of female - female relationships, not necessarily in a sexual way, but more about emotional connection and closeness.