Why do male squirrel monkeys wee on other squirrel monkeys?

Not all male squirrel monkeys do this, only the dominant squirrel monkey in the group will do this.
The dominant male squirrel monkey urinates on the other squirrel monkeys in the group to remind them that he is in charge and not them. Similarly, some animals urinate on their territory to warn others that they own it, it's a similar thing with squirrel monkeys.
Not all male squirrel monkeys do this, only the dominant squirrel monkey in the group will do this.
The dominant male squirrel monkey urinates on the other squirrel monkeys in the group to remind them that he is in charge and not them. Similarly, some animals urinate on their territory to warn others that they own it, it's a similar thing with squirrel monkeys.