You tend to have a lot of things on your mind at once, and you can be a little forgetful. So you keep a variety of COLORED STRINGS on your fingers as reminders. Each one means there is something different to remember at a certain time.
In fact, looking at your index finger reminds you that there is something important to remember now! It is your friend John's birthday. The green string reminds you that John's birthday package will arrive today. The blue string ALSO reminds you that John's birthday package will arrive today, though in a way that means something slightly different.
You are further reminded that you have some things to do outside your house soon. But you should stop by your room first for some supplies, and most importantly, to see if John is online and wish him a happy birthday!