It is a question Captain of the Guard Night Light asks cadets at the guard academy every year as a condition for graduating and becoming full fledged guards, but this year he will have to ask his own son Shining Armor this question.
Princess Celestia's been dealing with some rather embrassing issues for so long, and she decides it's finally time to do something about it. Fortunately, she just so happens to have a sister and a student more than willing to lend a helping hoof.