Going up the tree means that when a team has new players to join, the process in which the fans of the team wait for which player to join is called going up the tree. This stem comes from the story made up by online friends.
Climbing a tree is not really climbing a tree, but a stem. Its origin is that one year, many media reported that Igua would join Arsenal, but later he joined Naples instead of what the report said.
About this incident, some netizens made up a story of entertaining the whole village to celebrate it, and climbed up the tree to find a place with a good signal just to receive the news. After the story spread, some people made videos of it as a script.
Since then, as long as a player may transfer to another team, the process of fans of that team waiting for the player to transfer is called climbing the tree.