I have so many friends whose kids simply forget to close the door after they remove something to eat from the refrigerator. They are not aware that doing so will reduce the efficiency of the refrigerator and increase power bills too.
The refrigerator needs most of the power totally consumed in your home. So it is important that we should make it a habit to save as much energy as possible. You should open the fridge door only for a little time and close it as soon as you are done. It also helps if you adjust the fridge to a low setting in winter.