If you answered yes or no, then you need shampoo.
Shampoo is a complicated substance of infinite constitution and utility.
Shampoo is supposed to make you believe that you are a part of something larger than yourself. Shampoo is a smart person that can untangle your hair's illlogic. Shampoo is the most coldly rational of all the toiletries. There is shampoo to make your hair smell like apricots, and shampoo designed to make babies cry. You need to use a lot of some shampoo, and others require you to use less.