Since childhood, our parents showed us that it is a quality to share, that it is the last candy, or else our emotions and the deepest fright. However, when it is a question of sharing some personal things, there is a border marked well which you should not cross for the good of your own health.
It is so: you should not share hats or any other object which covers or touches your head (among which brushes, combs and Thai of pillow). You already know surely the magic with which combs and brushes spread lice, notably to the school. However, the same not desirable guests of the scalp can appear having slept on the cushion of another person or worn the hat of a friend.
Then next time when you need to cover your head, assure you that the hat which you use is yours.
One of the ways of protecting the skin is to buy products in hermetic bottles which avoid the development of bacteria.